diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8346299..a56e80b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## Unreleased
+
+- Tax rates, customer groups and currency rates as cache entries in the local files: no select per request for them. A tax rule, rate, class or group save cleans the tax entries; a rate import cleans the currency entries.
+- A process keeps the entries it read in memory until they expire; a worker answers them without the include.
+
 ## 0.2.0-rc7
 
 - Promote entries that Mage-OS stores through its compression decorator to the local files; the lifetime rule reads the packed record as the frontend answers it.
diff --git a/dev/README.md b/dev/README.md
index 31eefb3..0a097f1 100644
--- a/dev/README.md
+++ b/dev/README.md
@@ -27,6 +27,9 @@ Production installs use the default-enabled optimizations. These switches suppor
 | `view_config` | Reuse of theme/area view XML as PHP data. | Yes |
 | `guest_tax_factor` | Reuse of guest tax-factor calculations. | Yes |
 | `placeholder_url` | Cached placeholder URLs, including theme and transport identity. | Yes |
+| `tax_rates` | Tax rates and applied rates per rate request from the cache, for requests that are not customer-specific. | Yes |
+| `customer_groups` | Customer groups by id from the cache, with their excluded websites. | Yes |
+| `currency_rates` | Currency rates from the cache; a rate import cleans them. | Yes |
 
 These switches do not enable PHP class preload; that requires `opcache.preload` at FPM startup.
 
diff --git a/src/FastBoot/Plugin/Customer/GroupFromCache.php b/src/FastBoot/Plugin/Customer/GroupFromCache.php
new file mode 100644
index 0000000..854997a
--- /dev/null
+++ b/src/FastBoot/Plugin/Customer/GroupFromCache.php
@@ -0,0 +1,65 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBoot\Plugin\Customer;
+
+use GraphCommerce\FastBootCache\Model\Feature;
+use GraphCommerce\FastBootCache\Model\Tag;
+use Magento\Customer\Api\Data\GroupInterface;
+use Magento\Customer\Api\Data\GroupInterfaceFactory;
+use Magento\Customer\Api\GroupRepositoryInterface;
+use Magento\Framework\App\Cache\Type\Config as ConfigCache;
+use Magento\Framework\App\CacheInterface;
+use Magento\Framework\Api\ExtensionAttributesFactory;
+
+/**
+ * A customer group by id from the cache: its code, tax class and excluded websites, as the
+ * repository and core's excluded-website plugin answer them. A group or tax class save
+ * cleans the entries. The plugin wraps core's excluded-website plugin, so the entry holds
+ * its result.
+ */
+class GroupFromCache
+{
+    private const SWITCH = 'customer_groups';
+    private const KEY = 'FASTBOOT_GROUP_';
+
+    public function __construct(
+        private readonly CacheInterface $cache,
+        private readonly Feature $feature,
+        private readonly GroupInterfaceFactory $groupFactory,
+        private readonly ExtensionAttributesFactory $extensionFactory,
+    ) {
+    }
+
+    public function aroundGetById(GroupRepositoryInterface $subject, callable $proceed, $id): GroupInterface
+    {
+        if (!$this->feature->on(self::SWITCH)) {
+            return $proceed($id);
+        }
+        $key = self::KEY . (int)$id;
+        $cached = $this->cache->load($key);
+        $data = is_string($cached) ? json_decode($cached, true) : null;
+        if (is_array($data)) {
+            $group = $this->groupFactory->create()
+                ->setId($data['id'])
+                ->setCode($data['code'])
+                ->setTaxClassId($data['tax_class_id'])
+                ->setTaxClassName($data['tax_class_name']);
+            if ($data['exclude_website_ids']) {
+                $group->setExtensionAttributes($this->extensionFactory->create(GroupInterface::class)->setExcludeWebsiteIds($data['exclude_website_ids']));
+            }
+
+            return $group;
+        }
+        $group = $proceed($id);
+        $this->cache->save(json_encode([
+            'id' => $group->getId(),
+            'code' => $group->getCode(),
+            'tax_class_id' => $group->getTaxClassId(),
+            'tax_class_name' => $group->getTaxClassName(),
+            'exclude_website_ids' => $group->getExtensionAttributes()?->getExcludeWebsiteIds() ?? [],
+        ]), $key, [ConfigCache::CACHE_TAG, Tag::TAX]);
+
+        return $group;
+    }
+}
diff --git a/src/FastBoot/Plugin/Directory/CurrencyRatesFromCache.php b/src/FastBoot/Plugin/Directory/CurrencyRatesFromCache.php
new file mode 100644
index 0000000..9926fa0
--- /dev/null
+++ b/src/FastBoot/Plugin/Directory/CurrencyRatesFromCache.php
@@ -0,0 +1,63 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBoot\Plugin\Directory;
+
+use GraphCommerce\FastBootCache\Model\Feature;
+use GraphCommerce\FastBootCache\Model\Tag;
+use Magento\Directory\Model\Currency as CurrencyModel;
+use Magento\Directory\Model\ResourceModel\Currency;
+use Magento\Framework\App\Cache\Type\Config as ConfigCache;
+use Magento\Framework\App\CacheInterface;
+
+/**
+ * A currency rate from the cache instead of a select per request; a rate import cleans the
+ * entries. A missing rate is an entry too, as core answers false for it.
+ */
+class CurrencyRatesFromCache
+{
+    private const SWITCH = 'currency_rates';
+    private const KEY = 'FASTBOOT_CURRENCY_RATE_';
+
+    public function __construct(
+        private readonly CacheInterface $cache,
+        private readonly Feature $feature,
+    ) {
+    }
+
+    public function aroundGetRate(Currency $subject, callable $proceed, $currencyFrom, $currencyTo)
+    {
+        return $this->rate('rate', $currencyFrom, $currencyTo, static fn() => $proceed($currencyFrom, $currencyTo));
+    }
+
+    public function aroundGetAnyRate(Currency $subject, callable $proceed, $currencyFrom, $currencyTo)
+    {
+        return $this->rate('any', $currencyFrom, $currencyTo, static fn() => $proceed($currencyFrom, $currencyTo));
+    }
+
+    public function afterSaveRates(Currency $subject, $result)
+    {
+        $this->cache->clean([Tag::CURRENCY]);
+
+        return $result;
+    }
+
+    private function rate(string $kind, $currencyFrom, $currencyTo, callable $compute)
+    {
+        $from = strtoupper($currencyFrom instanceof CurrencyModel ? (string)$currencyFrom->getCode() : (string)$currencyFrom);
+        $to = strtoupper($currencyTo instanceof CurrencyModel ? (string)$currencyTo->getCode() : (string)$currencyTo);
+        if ($from === $to || !$this->feature->on(self::SWITCH)) {
+            return $compute();
+        }
+        $key = self::KEY . $kind . '_' . $from . '_' . $to;
+        $cached = $this->cache->load($key);
+        $entry = is_string($cached) ? json_decode($cached, true) : null;
+        if (is_array($entry) && array_key_exists('rate', $entry)) {
+            return $entry['rate'];
+        }
+        $rate = $compute();
+        $this->cache->save(json_encode(['rate' => $rate], JSON_PRESERVE_ZERO_FRACTION), $key, [ConfigCache::CACHE_TAG, Tag::CURRENCY]);
+
+        return $rate;
+    }
+}
diff --git a/src/FastBoot/Plugin/Tax/ForgetRates.php b/src/FastBoot/Plugin/Tax/ForgetRates.php
new file mode 100644
index 0000000..b7903c2
--- /dev/null
+++ b/src/FastBoot/Plugin/Tax/ForgetRates.php
@@ -0,0 +1,33 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBoot\Plugin\Tax;
+
+use GraphCommerce\FastBootCache\Model\Tag;
+use Magento\Framework\App\CacheInterface;
+
+/**
+ * A tax rule, rate or class save or delete, and a customer group save or delete, drop the
+ * tax entries: the rates, the groups and the guest tax factor.
+ */
+class ForgetRates
+{
+    public function __construct(
+        private readonly CacheInterface $cache,
+    ) {
+    }
+
+    public function afterSave($subject, $result)
+    {
+        $this->cache->clean([Tag::TAX]);
+
+        return $result;
+    }
+
+    public function afterDelete($subject, $result)
+    {
+        $this->cache->clean([Tag::TAX]);
+
+        return $result;
+    }
+}
diff --git a/src/FastBoot/Plugin/Tax/RatesFromCache.php b/src/FastBoot/Plugin/Tax/RatesFromCache.php
new file mode 100644
index 0000000..906b819
--- /dev/null
+++ b/src/FastBoot/Plugin/Tax/RatesFromCache.php
@@ -0,0 +1,73 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBoot\Plugin\Tax;
+
+use GraphCommerce\FastBootCache\Model\Feature;
+use GraphCommerce\FastBootCache\Model\Tag;
+use Magento\Authorization\Model\UserContextInterface;
+use Magento\Framework\App\Cache\Type\Config as ConfigCache;
+use Magento\Framework\App\CacheInterface;
+use Magento\Store\Model\StoreManagerInterface;
+use Magento\Tax\Model\ResourceModel\Calculation;
+
+/**
+ * The tax rate and the applied rates of a rate request from the cache, keyed as core's
+ * calculation keys its own per-request memory: store, product and customer tax class,
+ * country, region and postcode. A tax rule, rate or class save cleans the entries. A
+ * signed-in customer's request carries the customer's own address, one entry per
+ * address, so it stays with core's per-request memory.
+ */
+class RatesFromCache
+{
+    private const SWITCH = 'tax_rates';
+    private const KEY = 'FASTBOOT_TAX_RATE_';
+
+    public function __construct(
+        private readonly CacheInterface $cache,
+        private readonly Feature $feature,
+        private readonly StoreManagerInterface $storeManager,
+        private readonly UserContextInterface $userContext,
+    ) {
+    }
+
+    public function aroundGetRateInfo(Calculation $subject, callable $proceed, $request): array
+    {
+        return $this->entry('info', $request, static fn(): array => $proceed($request));
+    }
+
+    public function aroundGetCalculationProcess(Calculation $subject, callable $proceed, $request, $rates = null): array
+    {
+        if ($rates !== null) {
+            return $proceed($request, $rates);
+        }
+
+        return $this->entry('process', $request, static fn(): array => $proceed($request));
+    }
+
+    private function entry(string $kind, $request, callable $compute): array
+    {
+        if (!$this->feature->on(self::SWITCH) || (int)$this->userContext->getUserType() === UserContextInterface::USER_TYPE_CUSTOMER) {
+            return $compute();
+        }
+        $key = self::KEY . $kind . '_' . md5(implode('|', [
+            $this->storeManager->getStore($request->getStore())->getId(),
+            implode(',', (array)$request->getProductClassId()),
+            $request->getCustomerClassId(),
+            $request->getCountryId(),
+            $request->getRegionId(),
+            $request->getPostcode(),
+        ]));
+        $cached = $this->cache->load($key);
+        if (is_string($cached)) {
+            $value = json_decode($cached, true);
+            if (is_array($value)) {
+                return $value;
+            }
+        }
+        $value = $compute();
+        $this->cache->save(json_encode($value, JSON_PRESERVE_ZERO_FRACTION), $key, [ConfigCache::CACHE_TAG, Tag::TAX]);
+
+        return $value;
+    }
+}
diff --git a/src/FastBoot/Test/Unit/Plugin/Customer/GroupFromCacheTest.php b/src/FastBoot/Test/Unit/Plugin/Customer/GroupFromCacheTest.php
new file mode 100644
index 0000000..5eafa49
--- /dev/null
+++ b/src/FastBoot/Test/Unit/Plugin/Customer/GroupFromCacheTest.php
@@ -0,0 +1,90 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBoot\Test\Unit\Plugin\Customer;
+
+use GraphCommerce\FastBoot\Plugin\Customer\GroupFromCache;
+use GraphCommerce\FastBootCache\Model\Feature;
+use Magento\Customer\Api\Data\GroupExtension;
+use Magento\Customer\Api\Data\GroupInterface;
+use Magento\Customer\Api\Data\GroupInterfaceFactory;
+use Magento\Customer\Api\GroupRepositoryInterface;
+use Magento\Framework\Api\ExtensionAttributesFactory;
+use Magento\Framework\App\CacheInterface;
+use Magento\Framework\DataObject;
+use PHPUnit\Framework\TestCase;
+
+require_once __DIR__ . '/../../_files/customer-group-generated.php';
+
+class GroupFromCacheTest extends TestCase
+{
+    private array $entries = [];
+
+    private function plugin(): GroupFromCache
+    {
+        $cache = $this->createStub(CacheInterface::class);
+        $cache->method('load')->willReturnCallback(fn(string $id) => $this->entries[$id] ?? false);
+        $cache->method('save')->willReturnCallback(function (string $data, string $id) {
+            $this->entries[$id] = $data;
+
+            return true;
+        });
+        $feature = $this->createStub(Feature::class);
+        $feature->method('on')->willReturn(true);
+        $groups = $this->createStub(GroupInterfaceFactory::class);
+        $groups->method('create')->willReturnCallback(fn(): GroupInterface => $this->group());
+        $extensions = $this->createStub(ExtensionAttributesFactory::class);
+        $extensions->method('create')->willReturnCallback(static fn(): GroupExtension => new GroupExtension());
+
+        return new GroupFromCache($cache, $feature, $groups, $extensions);
+    }
+
+    /** A group data object that keeps what its setters receive. */
+    private function group(): GroupInterface
+    {
+        return new class extends DataObject implements GroupInterface {
+            public function getId() { return $this->getData('id'); }
+            public function setId($id) { return $this->setData('id', $id); }
+            public function getCode() { return $this->getData('code'); }
+            public function setCode($code) { return $this->setData('code', $code); }
+            public function getTaxClassId() { return $this->getData('tax_class_id'); }
+            public function setTaxClassId($taxClassId) { return $this->setData('tax_class_id', $taxClassId); }
+            public function getTaxClassName() { return $this->getData('tax_class_name'); }
+            public function setTaxClassName($taxClassName) { return $this->setData('tax_class_name', $taxClassName); }
+            public function getExtensionAttributes() { return $this->getData('extension_attributes'); }
+            public function setExtensionAttributes(\Magento\Customer\Api\Data\GroupExtensionInterface $extensionAttributes) { return $this->setData('extension_attributes', $extensionAttributes); }
+        };
+    }
+
+    public function testAGroupWithExcludedWebsitesComesBackWholeFromTheEntry(): void
+    {
+        $plugin = $this->plugin();
+        $subject = $this->createStub(GroupRepositoryInterface::class);
+        $calls = 0;
+        $proceed = function () use (&$calls): GroupInterface {
+            $calls++;
+            $group = $this->group()->setId(3)->setCode('Wholesale')->setTaxClassId(5)->setTaxClassName('Retail Customer');
+
+            return $group->setExtensionAttributes((new GroupExtension())->setExcludeWebsiteIds([2]));
+        };
+        $plugin->aroundGetById($subject, $proceed, 3);
+        $group = $plugin->aroundGetById($subject, $proceed, 3);
+        self::assertSame(1, $calls);
+        self::assertSame(3, $group->getId());
+        self::assertSame('Wholesale', $group->getCode());
+        self::assertSame(5, $group->getTaxClassId());
+        self::assertSame('Retail Customer', $group->getTaxClassName());
+        self::assertSame([2], $group->getExtensionAttributes()->getExcludeWebsiteIds());
+    }
+
+    public function testAGroupWithoutExcludedWebsitesCarriesNoExtensionAttributes(): void
+    {
+        $plugin = $this->plugin();
+        $subject = $this->createStub(GroupRepositoryInterface::class);
+        $proceed = fn(): GroupInterface => $this->group()->setId(0)->setCode('NOT LOGGED IN')->setTaxClassId(3)->setTaxClassName('Retail Customer');
+        $plugin->aroundGetById($subject, $proceed, 0);
+        $group = $plugin->aroundGetById($subject, $proceed, 0);
+        self::assertSame('NOT LOGGED IN', $group->getCode());
+        self::assertNull($group->getExtensionAttributes());
+    }
+}
diff --git a/src/FastBoot/Test/Unit/Plugin/Directory/CurrencyRatesFromCacheTest.php b/src/FastBoot/Test/Unit/Plugin/Directory/CurrencyRatesFromCacheTest.php
new file mode 100644
index 0000000..ee82da4
--- /dev/null
+++ b/src/FastBoot/Test/Unit/Plugin/Directory/CurrencyRatesFromCacheTest.php
@@ -0,0 +1,54 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBoot\Test\Unit\Plugin\Directory;
+
+use GraphCommerce\FastBoot\Plugin\Directory\CurrencyRatesFromCache;
+use GraphCommerce\FastBootCache\Model\Feature;
+use GraphCommerce\FastBootCache\Model\Tag;
+use Magento\Directory\Model\ResourceModel\Currency;
+use Magento\Framework\App\CacheInterface;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+class CurrencyRatesFromCacheTest extends TestCase
+{
+    private array $entries = [];
+    private CacheInterface&MockObject $cache;
+
+    private function plugin(): CurrencyRatesFromCache
+    {
+        $this->cache = $this->createMock(CacheInterface::class);
+        $this->cache->method('load')->willReturnCallback(fn(string $id) => $this->entries[$id] ?? false);
+        $this->cache->method('save')->willReturnCallback(function (string $data, string $id) {
+            $this->entries[$id] = $data;
+
+            return true;
+        });
+        $feature = $this->createStub(Feature::class);
+        $feature->method('on')->willReturn(true);
+
+        return new CurrencyRatesFromCache($this->cache, $feature);
+    }
+
+    public function testARateAndAMissingRateAreEntriesAndARateImportCleansThem(): void
+    {
+        $plugin = $this->plugin();
+        $subject = $this->createStub(Currency::class);
+        $calls = 0;
+        $proceed = function () use (&$calls) {
+            $calls++;
+
+            return $calls === 1 ? '0.8500' : false;
+        };
+        self::assertSame('0.8500', $plugin->aroundGetRate($subject, $proceed, 'EUR', 'usd'));
+        self::assertSame('0.8500', $plugin->aroundGetRate($subject, $proceed, 'eur', 'USD'));
+        self::assertFalse($plugin->aroundGetAnyRate($subject, $proceed, 'EUR', 'GBP'));
+        self::assertFalse($plugin->aroundGetAnyRate($subject, $proceed, 'EUR', 'GBP'));
+        self::assertSame(2, $calls);
+        self::assertSame(1, $plugin->aroundGetRate($subject, static fn() => 1, 'EUR', 'EUR'));
+        self::assertCount(2, $this->entries);
+        $this->cache->expects(self::once())->method('clean')->with([Tag::CURRENCY]);
+        $plugin->afterSaveRates($subject, null);
+    }
+}
diff --git a/src/FastBoot/Test/Unit/Plugin/Tax/RatesFromCacheTest.php b/src/FastBoot/Test/Unit/Plugin/Tax/RatesFromCacheTest.php
new file mode 100644
index 0000000..bac77c1
--- /dev/null
+++ b/src/FastBoot/Test/Unit/Plugin/Tax/RatesFromCacheTest.php
@@ -0,0 +1,95 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBoot\Test\Unit\Plugin\Tax;
+
+use GraphCommerce\FastBoot\Plugin\Tax\RatesFromCache;
+use GraphCommerce\FastBootCache\Model\Feature;
+use GraphCommerce\FastBootCache\Model\Tag;
+use Magento\Authorization\Model\UserContextInterface;
+use Magento\Framework\App\CacheInterface;
+use Magento\Framework\DataObject;
+use Magento\Store\Api\Data\StoreInterface;
+use Magento\Store\Model\StoreManagerInterface;
+use Magento\Tax\Model\ResourceModel\Calculation;
+use PHPUnit\Framework\TestCase;
+
+class RatesFromCacheTest extends TestCase
+{
+    /** @var array<string, string> */
+    private array $entries = [];
+    private array $tags = [];
+
+    private function plugin(bool $on = true, int $userType = UserContextInterface::USER_TYPE_GUEST): RatesFromCache
+    {
+        $cache = $this->createStub(CacheInterface::class);
+        $cache->method('load')->willReturnCallback(fn(string $id) => $this->entries[$id] ?? false);
+        $cache->method('save')->willReturnCallback(function (string $data, string $id, array $tags) {
+            $this->entries[$id] = $data;
+            $this->tags[$id] = $tags;
+
+            return true;
+        });
+        $feature = $this->createStub(Feature::class);
+        $feature->method('on')->willReturn($on);
+        $store = $this->createStub(StoreInterface::class);
+        $store->method('getId')->willReturn(1);
+        $stores = $this->createStub(StoreManagerInterface::class);
+        $stores->method('getStore')->willReturn($store);
+
+        $user = $this->createStub(UserContextInterface::class);
+        $user->method('getUserType')->willReturn($userType);
+
+        return new RatesFromCache($cache, $feature, $stores, $user);
+    }
+
+    private function request(string $country = 'NL', int $productClass = 2): DataObject
+    {
+        return new DataObject(['store' => 1, 'product_class_id' => $productClass, 'customer_class_id' => 3, 'country_id' => $country, 'region_id' => 0, 'postcode' => '*']);
+    }
+
+    public function testTheRateInfoOfARequestKeyIsComputedOnceAndTaggedForTaxSaves(): void
+    {
+        $plugin = $this->plugin();
+        $subject = $this->createStub(Calculation::class);
+        $calls = 0;
+        $proceed = function () use (&$calls): array {
+            $calls++;
+
+            return ['process' => [['id' => 'NL', 'percent' => 21.0, 'rates' => [['code' => 'NL', 'title' => 'BTW', 'percent' => 21.0, 'position' => 1, 'priority' => 1]]]], 'value' => 21.0];
+        };
+        $first = $plugin->aroundGetRateInfo($subject, $proceed, $this->request());
+        $second = $plugin->aroundGetRateInfo($subject, $proceed, $this->request());
+        self::assertSame(1, $calls);
+        self::assertSame($first, $second);
+        self::assertSame(21.0, $second['value']);
+        self::assertContains(Tag::TAX, $this->tags[array_key_first($this->tags)]);
+        $plugin->aroundGetRateInfo($subject, $proceed, $this->request('DE'));
+        self::assertSame(2, $calls, 'Another destination is another entry');
+    }
+
+    public function testGivenRatesAnOffSwitchAndACustomerRequestBypassTheCache(): void
+    {
+        $subject = $this->createStub(Calculation::class);
+        $calls = 0;
+        $proceed = function () use (&$calls): array {
+            $calls++;
+
+            return [];
+        };
+        $plugin = $this->plugin();
+        $plugin->aroundGetCalculationProcess($subject, $proceed, $this->request(), [['code' => 'x']]);
+        $plugin->aroundGetCalculationProcess($subject, $proceed, $this->request(), [['code' => 'x']]);
+        self::assertSame(2, $calls);
+        self::assertSame([], $this->entries);
+        $off = $this->plugin(false);
+        $off->aroundGetCalculationProcess($subject, $proceed, $this->request());
+        $off->aroundGetCalculationProcess($subject, $proceed, $this->request());
+        self::assertSame(4, $calls);
+        $customer = $this->plugin(true, UserContextInterface::USER_TYPE_CUSTOMER);
+        $customer->aroundGetRateInfo($subject, $proceed, $this->request());
+        $customer->aroundGetRateInfo($subject, $proceed, $this->request());
+        self::assertSame(6, $calls, 'A customer request keeps its own address out of the entries');
+        self::assertSame([], $this->entries);
+    }
+}
diff --git a/src/FastBoot/Test/Unit/_files/customer-group-generated.php b/src/FastBoot/Test/Unit/_files/customer-group-generated.php
new file mode 100644
index 0000000..ebdb35e
--- /dev/null
+++ b/src/FastBoot/Test/Unit/_files/customer-group-generated.php
@@ -0,0 +1,39 @@
+<?php
+/**
+ * The generated customer group classes, for a unit run without Magento's generated code.
+ */
+declare(strict_types=1);
+
+namespace Magento\Customer\Api\Data;
+
+if (!interface_exists(GroupExtensionInterface::class)) {
+    interface GroupExtensionInterface extends \Magento\Framework\Api\ExtensionAttributesInterface
+    {
+        public function getExcludeWebsiteIds();
+
+        public function setExcludeWebsiteIds($excludeWebsiteIds);
+    }
+
+    class GroupExtension extends \Magento\Framework\Api\AbstractSimpleObject implements GroupExtensionInterface
+    {
+        public function getExcludeWebsiteIds()
+        {
+            return $this->_get('exclude_website_ids');
+        }
+
+        public function setExcludeWebsiteIds($excludeWebsiteIds)
+        {
+            return $this->setData('exclude_website_ids', $excludeWebsiteIds);
+        }
+    }
+}
+
+if (!class_exists(GroupInterfaceFactory::class)) {
+    class GroupInterfaceFactory
+    {
+        public function create(array $data = []): GroupInterface
+        {
+            throw new \LogicException('The test stubs the factory');
+        }
+    }
+}
diff --git a/src/FastBoot/etc/di.xml b/src/FastBoot/etc/di.xml
index 1779d7e..0bf2428 100644
--- a/src/FastBoot/etc/di.xml
+++ b/src/FastBoot/etc/di.xml
@@ -7,7 +7,13 @@
                 <item name="scopes" xsi:type="string">FASTBOOT_SCOPES</item>
                 <item name="config_unchanged" xsi:type="string">FASTBOOT_CONFIG_UNCHANGED_</item>
                 <item name="website_stores" xsi:type="string">FASTBOOT_WEBSITE_STORES_</item>
-                <item name="sort_by" xsi:type="string">PRODUCT_LISTING_SORT_BY_ATTRIBUTES</item>
+                <item name="tax_rates" xsi:type="string">FASTBOOT_TAX_RATE_</item>
+                <item name="groups" xsi:type="string">FASTBOOT_GROUP_</item>
+                <item name="currency_rates" xsi:type="string">FASTBOOT_CURRENCY_RATE_</item>
+            </argument>
+            <argument name="tags" xsi:type="array">
+                <item name="tax" xsi:type="const">GraphCommerce\FastBootCache\Model\Tag::TAX</item>
+                <item name="currency" xsi:type="const">GraphCommerce\FastBootCache\Model\Tag::CURRENCY</item>
             </argument>
         </arguments>
     </type>
@@ -53,6 +59,28 @@
     <type name="Magento\Store\Model\Group">
         <plugin name="graphcommerce_fastboot_default_store" type="GraphCommerce\FastBoot\Plugin\Store\DefaultStore"/>
     </type>
+    <!-- The tax rates, the customer groups and the currency rates from the cache instead of their selects per request; a save of the data cleans them. -->
+    <type name="Magento\Tax\Model\ResourceModel\Calculation">
+        <plugin name="graphcommerce_fastboot_tax_rates" type="GraphCommerce\FastBoot\Plugin\Tax\RatesFromCache"/>
+    </type>
+    <type name="Magento\Customer\Api\GroupRepositoryInterface">
+        <plugin name="graphcommerce_fastboot_customer_groups" type="GraphCommerce\FastBoot\Plugin\Customer\GroupFromCache" sortOrder="-10"/>
+    </type>
+    <type name="Magento\Directory\Model\ResourceModel\Currency">
+        <plugin name="graphcommerce_fastboot_currency_rates" type="GraphCommerce\FastBoot\Plugin\Directory\CurrencyRatesFromCache"/>
+    </type>
+    <type name="Magento\Tax\Model\ResourceModel\Calculation\Rate">
+        <plugin name="graphcommerce_fastboot_forget_rates" type="GraphCommerce\FastBoot\Plugin\Tax\ForgetRates"/>
+    </type>
+    <type name="Magento\Tax\Model\ResourceModel\Calculation\Rule">
+        <plugin name="graphcommerce_fastboot_forget_rates" type="GraphCommerce\FastBoot\Plugin\Tax\ForgetRates"/>
+    </type>
+    <type name="Magento\Tax\Model\ResourceModel\TaxClass">
+        <plugin name="graphcommerce_fastboot_forget_rates" type="GraphCommerce\FastBoot\Plugin\Tax\ForgetRates"/>
+    </type>
+    <type name="Magento\Customer\Model\ResourceModel\Group">
+        <plugin name="graphcommerce_fastboot_forget_rates" type="GraphCommerce\FastBoot\Plugin\Tax\ForgetRates"/>
+    </type>
 <type name="Magento\Deploy\Model\DeploymentConfig\Hash"><plugin name="graphcommerce_fastboot_deploy_hash_changed" type="GraphCommerce\FastBoot\Plugin\Deploy\ConfigUnchanged"/></type>
 <type name="Magento\Framework\Console\CommandList"><arguments><argument name="commands" xsi:type="array">
  <item name="fastboot_status" xsi:type="object">GraphCommerce\FastBoot\Console\StatusCommand</item>
diff --git a/src/FastBoot/etc/module.xml b/src/FastBoot/etc/module.xml
index c069bc5..6ea29ec 100644
--- a/src/FastBoot/etc/module.xml
+++ b/src/FastBoot/etc/module.xml
@@ -6,6 +6,10 @@
             <module name="Magento_Store"/>
             <module name="Magento_Config"/>
             <module name="Magento_Deploy"/>
+            <module name="Magento_Tax"/>
+            <module name="Magento_Authorization"/>
+            <module name="Magento_Customer"/>
+            <module name="Magento_Directory"/>
         </sequence>
     </module>
 </config>
diff --git a/src/FastBootCache/Model/Feature.php b/src/FastBootCache/Model/Feature.php
index 09dd5d2..486dc80 100644
--- a/src/FastBootCache/Model/Feature.php
+++ b/src/FastBootCache/Model/Feature.php
@@ -15,7 +15,7 @@
 class Feature
 {
     private ?array $switches = null;
-    private const CACHED = ['schema_array' => true,'cache_files' => true,'system_config_array' => true,'view_config' => true,'parsed_queries' => true,'validated_queries' => true,'scopes_cache' => true,'website_stores' => true,'deploy_config_unchanged' => true,'placeholder_url' => true,'guest_tax_factor' => true];
+    private const CACHED = ['schema_array' => true,'cache_files' => true,'system_config_array' => true,'view_config' => true,'parsed_queries' => true,'validated_queries' => true,'scopes_cache' => true,'website_stores' => true,'deploy_config_unchanged' => true,'placeholder_url' => true,'guest_tax_factor' => true,'tax_rates' => true,'customer_groups' => true,'currency_rates' => true];
 
     public function __construct(
         private readonly DeploymentConfig $deploymentConfig,
diff --git a/src/FastBootCache/Model/PhpFiles.php b/src/FastBootCache/Model/PhpFiles.php
index 7fc9d8e..1851d89 100644
--- a/src/FastBootCache/Model/PhpFiles.php
+++ b/src/FastBootCache/Model/PhpFiles.php
@@ -12,6 +12,9 @@
 class PhpFiles
 {
     private ?string $root = null;
+
+    /** @var array<string, array{value: mixed, expires: ?float}> the entries this process read or wrote, by index path */
+    private array $loaded = [];
     public const LOADED_LIFETIME = 0; // Unknown backend lifetimes must never be extended.
     public function __construct(private Filesystem $filesystem, private Version $version, private DeploymentConfig $deploymentConfig, private Release $release)
     {
@@ -44,6 +47,9 @@ public function read(string $group, string $id): mixed
             return null;
         }
         $index = $this->path($group, $id);
+        if (isset($this->loaded[$index]) && ($this->loaded[$index]['expires'] === null || $this->loaded[$index]['expires'] > microtime(true))) {
+            return $this->loaded[$index]['value'];
+        }
         $record = is_file($index) ? json_decode((string)@file_get_contents($index), true) : null;
         if (!is_array($record) || !isset($record['hash']) || !is_string($record['hash']) || !preg_match('/^[a-f0-9]{64}$/D', $record['hash']) || !array_key_exists('expires', $record) || ($record['expires'] !== null && !is_numeric($record['expires'])) || ($record['expires'] !== null && $record['expires'] <= microtime(true))) {
             return null;
@@ -65,8 +71,21 @@ public function read(string $group, string $id): mixed
             @unlink($file);
             return null;
         }
+        $this->remember($index, $value['value'], $record['expires'] === null ? null : (float)$record['expires']);
         return $value['value'];
     }
+
+    /**
+     * A worker process answers the entry from memory until it expires; the index path carries
+     * the version, so a bump leaves the memory behind.
+     */
+    private function remember(string $index, mixed $value, ?float $expires): void
+    {
+        if (count($this->loaded) >= 512) {
+            $this->loaded = [];
+        }
+        $this->loaded[$index] = ['value' => $value, 'expires' => $expires];
+    }
     public function write(string $group, string $id, mixed $value, ?int $lifeTime = null, ?string $expectedVersion = null): void
     {
         if ($this->release->id() === null) {
@@ -126,7 +145,10 @@ public function write(string $group, string $id, mixed $value, ?int $lifeTime =
             if (!is_dir(dirname($index)) && !@mkdir(dirname($index), 0700, true) && !is_dir(dirname($index))) {
                 return;
             }
-            $this->atomic($index, json_encode(['hash' => $hash,'expires' => $lifeTime === null ? null : microtime(true) + $lifeTime], JSON_THROW_ON_ERROR));
+            $expires = $lifeTime === null ? null : microtime(true) + $lifeTime;
+            if ($this->atomic($index, json_encode(['hash' => $hash,'expires' => $expires], JSON_THROW_ON_ERROR))) {
+                $this->remember($index, $value, $expires);
+            }
         } finally {
             flock($lock, LOCK_UN);
             fclose($lock);
@@ -162,11 +184,13 @@ private static function exportable(mixed $value, int $depth = 0): bool
     }
     public function remove(string $group, string $id): void
     {
+        unset($this->loaded[$this->path($group, $id)]);
         @unlink($this->path($group, $id));
     }
     /** Remove obsolete indexes only. Blobs stay reusable and bounded until release cleanup/FPM restart. */
     public function sweep(): void
     {
+        $this->loaded = [];
         $root = $this->namespaceDirectory().'/indexes';
         foreach (glob($root.'/*', GLOB_ONLYDIR) ?: [] as $dir) {
             $this->removeDirectory($dir);
diff --git a/src/FastBootCache/Model/Tag.php b/src/FastBootCache/Model/Tag.php
new file mode 100644
index 0000000..ebcb35a
--- /dev/null
+++ b/src/FastBootCache/Model/Tag.php
@@ -0,0 +1,14 @@
+<?php
+declare(strict_types=1);
+
+namespace GraphCommerce\FastBootCache\Model;
+
+/**
+ * The cache tags of the entries FastBoot keeps in the default frontend; a save of the
+ * data behind a tag cleans it, which sweeps the local files.
+ */
+final class Tag
+{
+    public const TAX = 'FASTBOOT_TAX';
+    public const CURRENCY = 'FASTBOOT_CURRENCY';
+}
diff --git a/src/FastBootCache/Test/Unit/Model/PhpFilesTest.php b/src/FastBootCache/Test/Unit/Model/PhpFilesTest.php
index 8c4952d..4a748db 100644
--- a/src/FastBootCache/Test/Unit/Model/PhpFilesTest.php
+++ b/src/FastBootCache/Test/Unit/Model/PhpFilesTest.php
@@ -55,8 +55,8 @@ public function testVersionsAreIsolatedButIdenticalPayloadReusesOneBlob(): void
         self::assertSame(['old' => true], $b->read('CONFIG', 'a/b'));
         self::assertSame('different', $b->read('CONFIG', 'a_b'));
         $b->sweep();
-        self::assertNull($a->read('CONFIG', 'a/b'));
         self::assertNull($b->read('CONFIG', 'a/b'));
+        self::assertNull($this->files('a')->read('CONFIG', 'a/b'), 'A sweep comes with a version bump, so another process reads under a new path');
     }
     public function testPublicationGenerationAndExpiryAreRespected(): void
     {
@@ -81,4 +81,19 @@ public function testAdmissionIsBoundedAndObjectsAreNeverExported(): void
         $f->write('CONFIG', 'object', new \stdClass());
         self::assertNull($f->read('CONFIG', 'object'));
     }
+
+    public function testAProcessAnswersAnEntryFromMemoryUntilItExpiresOrIsRemoved(): void
+    {
+        $files = $this->files('v1');
+        $files->write('G', 'kept', ['a' => 1]);
+        $files->write('G', 'brief', ['b' => 2], 1);
+        $this->remove($this->var.'/fastboot');
+        self::assertSame(['a' => 1], $files->read('G', 'kept'), 'The memory of this process answers after the files are gone');
+        self::assertSame(['b' => 2], $files->read('G', 'brief'));
+        usleep(1100000);
+        self::assertNull($files->read('G', 'brief'), 'An expired entry leaves the memory');
+        $files->remove('G', 'kept');
+        self::assertNull($files->read('G', 'kept'));
+        self::assertNull($this->files('v1')->read('G', 'kept'), 'Another process reads the files');
+    }
 }
diff --git a/src/FastBootGraphQl/Plugin/CacheId/GuestTaxFactor.php b/src/FastBootGraphQl/Plugin/CacheId/GuestTaxFactor.php
index ec216b2..053ce62 100644
--- a/src/FastBootGraphQl/Plugin/CacheId/GuestTaxFactor.php
+++ b/src/FastBootGraphQl/Plugin/CacheId/GuestTaxFactor.php
@@ -4,6 +4,7 @@
 namespace GraphCommerce\FastBootGraphQl\Plugin\CacheId;
 
 use GraphCommerce\FastBootCache\Model\Feature;
+use GraphCommerce\FastBootCache\Model\Tag;
 use Magento\CustomerGraphQl\CacheIdFactorProviders\CustomerTaxRateProvider;
 use Magento\Framework\App\Cache\Type\Config as ConfigCache;
 use Magento\Framework\App\CacheInterface;
@@ -21,7 +22,7 @@ class GuestTaxFactor
 {
     private const SWITCH = 'guest_tax_factor';
 
-    public const TAG = 'FASTBOOT_TAX';
+    public const TAG = Tag::TAX;
 
     private const KEY = 'FASTBOOT_TAX_FACTOR_';
 
diff --git a/src/FastBootGraphQl/Plugin/Tax/ForgetTaxFactors.php b/src/FastBootGraphQl/Plugin/Tax/ForgetTaxFactors.php
deleted file mode 100644
index 61a7f8c..0000000
--- a/src/FastBootGraphQl/Plugin/Tax/ForgetTaxFactors.php
+++ /dev/null
@@ -1,33 +0,0 @@
-<?php
-declare(strict_types=1);
-
-namespace GraphCommerce\FastBootGraphQl\Plugin\Tax;
-
-use GraphCommerce\FastBootGraphQl\Plugin\CacheId\GuestTaxFactor;
-use Magento\Framework\App\CacheInterface;
-
-/**
- * Drops the cached tax factors after a save or delete on the resource models
- * the factors derive from (di.xml: tax rates, rules, classes, customer groups).
- */
-class ForgetTaxFactors
-{
-    public function __construct(
-        private readonly CacheInterface $cache,
-    ) {
-    }
-
-    public function afterSave($subject, $result)
-    {
-        $this->cache->clean([GuestTaxFactor::TAG]);
-
-        return $result;
-    }
-
-    public function afterDelete($subject, $result)
-    {
-        $this->cache->clean([GuestTaxFactor::TAG]);
-
-        return $result;
-    }
-}
diff --git a/src/FastBootGraphQl/etc/di.xml b/src/FastBootGraphQl/etc/di.xml
index d5f092f..b81f447 100644
--- a/src/FastBootGraphQl/etc/di.xml
+++ b/src/FastBootGraphQl/etc/di.xml
@@ -40,18 +40,6 @@
     <type name="Magento\CustomerGraphQl\CacheIdFactorProviders\CustomerTaxRateProvider">
         <plugin name="graphcommerce_fastboot_guest_tax_factor" type="GraphCommerce\FastBootGraphQl\Plugin\CacheId\GuestTaxFactor"/>
     </type>
-    <type name="Magento\Tax\Model\ResourceModel\Calculation\Rate">
-        <plugin name="graphcommerce_fastboot_forget_tax_factors" type="GraphCommerce\FastBootGraphQl\Plugin\Tax\ForgetTaxFactors"/>
-    </type>
-    <type name="Magento\Tax\Model\ResourceModel\Calculation\Rule">
-        <plugin name="graphcommerce_fastboot_forget_tax_factors" type="GraphCommerce\FastBootGraphQl\Plugin\Tax\ForgetTaxFactors"/>
-    </type>
-    <type name="Magento\Tax\Model\ResourceModel\TaxClass">
-        <plugin name="graphcommerce_fastboot_forget_tax_factors" type="GraphCommerce\FastBootGraphQl\Plugin\Tax\ForgetTaxFactors"/>
-    </type>
-    <type name="Magento\Customer\Model\ResourceModel\Group">
-        <plugin name="graphcommerce_fastboot_forget_tax_factors" type="GraphCommerce\FastBootGraphQl\Plugin\Tax\ForgetTaxFactors"/>
-    </type>
 
     <!-- The placeholder image URL per store and image type from the cache. -->
     <type name="Magento\CatalogGraphQl\Model\Resolver\Products\DataProvider\Image\Placeholder">