diff --git a/extension.json b/extension.json
index 5752fabe..4344d72f 100644
--- a/extension.json
+++ b/extension.json
@@ -42,6 +42,9 @@
 	"AutoloadNamespaces": {
 		"MediaWiki\\Extension\\CategoryTree\\": "includes/"
 	},
+	"TestAutoloadNamespaces": {
+		"MediaWiki\\Extension\\CategoryTree\\Tests\\": "tests/phpunit/"
+	},
 	"ResourceModules": {
 		"ext.categoryTree": {
 			"localBasePath": "modules/ext.categoryTree",
@@ -89,7 +92,7 @@
 	"HookHandlers": {
 		"default": {
 			"class": "MediaWiki\\Extension\\CategoryTree\\Hooks",
-			"services": [ "DBLoadBalancer", "MainConfig" ]
+			"services": [ "CategoryTree.CategoryCache", "MainConfig" ]
 		},
 		"config": {
 			"class": "MediaWiki\\Extension\\CategoryTree\\ConfigHookHandler"
@@ -183,5 +186,8 @@
 			}
 		}
 	},
+	"ServiceWiringFiles": [
+		"includes/ServiceWiring.php"
+	],
 	"manifest_version": 2
 }
diff --git a/includes/CategoryCache.php b/includes/CategoryCache.php
new file mode 100644
index 00000000..a54620f0
--- /dev/null
+++ b/includes/CategoryCache.php
@@ -0,0 +1,99 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\Extension\CategoryTree;
+
+use Category;
+use MediaWiki\Linker\LinkTarget;
+use Wikimedia\Rdbms\ILoadBalancer;
+
+/**
+ * Caches Category::class objects
+ */
+class CategoryCache {
+	/** @var (?Category)[] Keys are category database names, values are either a Category object or null */
+	private $cache = [];
+
+	/** @var ILoadBalancer */
+	private $loadBalancer;
+
+	/**
+	 * @param ILoadBalancer $loadBalancer
+	 */
+	public function __construct(
+		ILoadBalancer $loadBalancer
+	) {
+		$this->loadBalancer = $loadBalancer;
+	}
+
+	/**
+	 * Get a preloaded Category object or null when the Category does not exists. Loaded the Category on demand,
+	 * if not in cache, use self::doQuery when requesting a high number of category
+	 * @param LinkTarget $categoryTarget
+	 * @return ?Category
+	 */
+	public function getCategory( LinkTarget $categoryTarget ): ?Category {
+		if ( $categoryTarget->getNamespace() !== NS_CATEGORY ) {
+			return null;
+		}
+		$categoryDbKey = $categoryTarget->getDBkey();
+
+		if ( !array_key_exists( $categoryDbKey, $this->cache ) ) {
+			$this->doQuery( [ $categoryTarget ] );
+		}
+
+		return $this->cache[$categoryDbKey];
+	}
+
+	/**
+	 * Preloads category counts in this cache
+	 * @param LinkTarget[] $linkTargets
+	 */
+	public function doQuery( array $linkTargets ): void {
+		$categoryDbKeys = [];
+		foreach ( $linkTargets as $linkTarget ) {
+			if ( $linkTarget->getNamespace() !== NS_CATEGORY ) {
+				continue;
+			}
+			$categoryDbKey = $linkTarget->getDBkey();
+			if ( !array_key_exists( $categoryDbKey, $this->cache ) ) {
+				$categoryDbKeys[] = $categoryDbKey;
+				// To cache db misses, also avoid duplicates in the db query
+				$this->cache[$categoryDbKey] = null;
+			}
+		}
+		if ( $categoryDbKeys === [] ) {
+			return;
+		}
+
+		$rows = $this->loadBalancer->getConnection( ILoadBalancer::DB_REPLICA )
+			->newSelectQueryBuilder()
+			->select( [ 'cat_id', 'cat_title', 'cat_pages', 'cat_subcats', 'cat_files' ] )
+			->from( 'category' )
+			->where( [ 'cat_title' => $categoryDbKeys ] )
+			->caller( __METHOD__ )
+			->fetchResultSet();
+
+		foreach ( $rows as $row ) {
+			$this->cache[$row->cat_title] = Category::newFromRow( $row );
+		}
+	}
+
+}
diff --git a/includes/Hooks.php b/includes/Hooks.php
index a0320927..0ce51567 100644
--- a/includes/Hooks.php
+++ b/includes/Hooks.php
@@ -25,7 +25,6 @@
 namespace MediaWiki\Extension\CategoryTree;
 
 use Article;
-use Category;
 use Config;
 use Html;
 use IContextSource;
@@ -35,6 +34,7 @@ use MediaWiki\Hook\ParserFirstCallInitHook;
 use MediaWiki\Hook\SkinBuildSidebarHook;
 use MediaWiki\Hook\SpecialTrackingCategories__generateCatLinkHook;
 use MediaWiki\Hook\SpecialTrackingCategories__preprocessHook;
+use MediaWiki\Linker\LinkTarget;
 use MediaWiki\Page\Hook\ArticleFromTitleHook;
 use OutputPage;
 use Parser;
@@ -44,7 +44,6 @@ use Sanitizer;
 use Skin;
 use SpecialPage;
 use Title;
-use Wikimedia\Rdbms\ILoadBalancer;
 
 /**
  * Hooks for the CategoryTree extension, an AJAX based gadget
@@ -64,8 +63,8 @@ class Hooks implements
 
 	private const EXTENSION_DATA_FLAG = 'CategoryTree';
 
-	/** @var ILoadBalancer */
-	private $loadBalancer;
+	/** @var CategoryCache */
+	private $categoryCache;
 
 	/**
 	 * @var Config
@@ -73,11 +72,11 @@ class Hooks implements
 	private $config;
 
 	/**
-	 * @param ILoadBalancer $loadBalancer
+	 * @param CategoryCache $categoryCache
 	 * @param Config $config
 	 */
-	public function __construct( ILoadBalancer $loadBalancer, Config $config ) {
-		$this->loadBalancer = $loadBalancer;
+	public function __construct( CategoryCache $categoryCache, Config $config ) {
+		$this->categoryCache = $categoryCache;
 		$this->config = $config;
 	}
 
@@ -283,52 +282,33 @@ class Hooks implements
 
 	/**
 	 * Hook handler for the SpecialTrackingCategories::preprocess hook
-	 * @suppress PhanUndeclaredProperty SpecialPage->categoryTreeCategories
 	 * @param SpecialPage $specialPage SpecialTrackingCategories object
-	 * @param array $trackingCategories [ 'msg' => Title, 'cats' => Title[] ]
-	 * @phan-param array<string,array{msg:Title,cats:Title[]}> $trackingCategories
+	 * @param array $trackingCategories [ 'msg' => LinkTarget, 'cats' => LinkTarget[] ]
+	 * @phan-param array<string,array{msg:LinkTarget,cats:LinkTarget[]}> $trackingCategories
 	 */
 	public function onSpecialTrackingCategories__preprocess(
 		$specialPage,
 		$trackingCategories
 	) {
-		$categoryDbKeys = [];
-		foreach ( $trackingCategories as $catMsg => $data ) {
+		$categoryTargets = [];
+		foreach ( $trackingCategories as $data ) {
 			foreach ( $data['cats'] as $catTitle ) {
-				$categoryDbKeys[] = $catTitle->getDbKey();
+				$categoryTargets[] = $catTitle;
 			}
 		}
-		$categories = [];
-		if ( $categoryDbKeys ) {
-			$dbr = $this->loadBalancer->getConnectionRef( DB_REPLICA );
-			$res = $dbr->select(
-				'category',
-				[ 'cat_id', 'cat_title', 'cat_pages', 'cat_subcats', 'cat_files' ],
-				[ 'cat_title' => array_unique( $categoryDbKeys ) ],
-				__METHOD__
-			);
-			foreach ( $res as $row ) {
-				$categories[$row->cat_title] = Category::newFromRow( $row );
-			}
-		}
-		$specialPage->categoryTreeCategories = $categories;
+		$this->categoryCache->doQuery( $categoryTargets );
 	}
 
 	/**
 	 * Hook handler for the SpecialTrackingCategories::generateCatLink hook
-	 * @suppress PhanUndeclaredProperty SpecialPage->categoryTreeCategories
 	 * @param SpecialPage $specialPage SpecialTrackingCategories object
-	 * @param Title $catTitle Title object of the linked category
+	 * @param LinkTarget $catTitle LinkTarget object of the linked category
 	 * @param string &$html Result html
 	 */
 	public function onSpecialTrackingCategories__generateCatLink( $specialPage,
 		$catTitle, &$html
 	) {
-		if ( !isset( $specialPage->categoryTreeCategories ) ) {
-			return;
-		}
-
-		$cat = $specialPage->categoryTreeCategories[$catTitle->getDBkey()] ?? null;
+		$cat = $this->categoryCache->getCategory( $catTitle );
 
 		$html .= CategoryTree::createCountString( $specialPage->getContext(), $cat, 0 );
 	}
diff --git a/includes/ServiceWiring.php b/includes/ServiceWiring.php
new file mode 100644
index 00000000..da55b85b
--- /dev/null
+++ b/includes/ServiceWiring.php
@@ -0,0 +1,40 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\Extension\CategoryTree;
+
+use MediaWiki\MediaWikiServices;
+
+// PHP unit does not understand code coverage for this file
+// as the @covers annotation cannot cover a specific file
+// This is fully tested in CategoryTreeServiceWiringTest.php
+// @codeCoverageIgnoreStart
+
+/**
+ * CategoryTree wiring for MediaWiki services.
+ */
+return [
+	'CategoryTree.CategoryCache' => static function ( MediaWikiServices $services ) {
+		return new CategoryCache(
+			$services->getDBLoadBalancer()
+		);
+	},
+];
+// @codeCoverageIgnoreEnd
diff --git a/tests/phpunit/CategoryCacheTest.php b/tests/phpunit/CategoryCacheTest.php
new file mode 100644
index 00000000..f271f07b
--- /dev/null
+++ b/tests/phpunit/CategoryCacheTest.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\Extension\CategoryTree\Tests;
+
+use Category;
+use MediaWiki\Extension\CategoryTree\CategoryCache;
+use MediaWikiIntegrationTestCase;
+use TitleValue;
+use Wikimedia\Rdbms\ILoadBalancer;
+use Wikimedia\TestingAccessWrapper;
+
+/**
+ * @group Database
+ * @covers \MediaWiki\Extension\CategoryTree\CategoryCache
+ */
+class CategoryCacheTest extends MediaWikiIntegrationTestCase {
+
+	public function testConstruct() {
+		new CategoryCache(
+			$this->createMock( ILoadBalancer::class )
+		);
+		$this->addToAssertionCount( 1 );
+	}
+
+	public function testDoQuery() {
+		// Create a row in the category table
+		$this->editPage(
+			new TitleValue( NS_MAIN, 'CategoryTreeCategoryCacheTest' ),
+			'[[Category:Exists]]'
+		);
+
+		$categoryCache = TestingAccessWrapper::newFromObject(
+			$this->getServiceContainer()->get( 'CategoryTree.CategoryCache' )
+		);
+
+		$categoryCache->doQuery( [
+			new TitleValue( NS_CATEGORY, 'Exists' ),
+			new TitleValue( NS_CATEGORY, 'Missed' ),
+		] );
+
+		$this->assertCount( 2, $categoryCache->cache );
+		$this->assertArrayHasKey( 'Exists', $categoryCache->cache );
+		$this->assertInstanceOf( Category::class, $categoryCache->cache['Exists'] );
+		$this->assertArrayHasKey( 'Missed', $categoryCache->cache );
+		$this->assertNull( $categoryCache->cache['Missed'] );
+	}
+
+	public function testGetCategory() {
+		// Create a row in the category table
+		$this->editPage(
+			new TitleValue( NS_MAIN, 'CategoryTreeCategoryCacheTest' ),
+			'[[Category:Exists]]'
+		);
+
+		$categoryCache = TestingAccessWrapper::newFromObject(
+			$this->getServiceContainer()->get( 'CategoryTree.CategoryCache' )
+		);
+		$title = new TitleValue( NS_CATEGORY, 'Exists' );
+
+		// Test for cache miss
+		$this->assertCount( 0, $categoryCache->cache );
+		$this->assertInstanceOf( Category::class, $categoryCache->getCategory( $title ) );
+		$this->assertCount( 1, $categoryCache->cache );
+
+		// Test normal access
+		$this->assertInstanceOf( Category::class, $categoryCache->getCategory( $title ) );
+	}
+}
diff --git a/tests/phpunit/CategoryTreeServiceWiringTest.php b/tests/phpunit/CategoryTreeServiceWiringTest.php
new file mode 100644
index 00000000..fdaf3aeb
--- /dev/null
+++ b/tests/phpunit/CategoryTreeServiceWiringTest.php
@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * Copy of CentralAuth's CentralAuthServiceWiringTest.php
+ * as it could not be included as it's in another extension.
+ */
+
+use MediaWiki\MediaWikiServices;
+
+/**
+ * @coversNothing
+ */
+class CategoryTreeServiceWiringTest extends MediaWikiIntegrationTestCase {
+	/**
+	 * @dataProvider provideService
+	 */
+	public function testService( string $name ) {
+		MediaWikiServices::getInstance()->get( $name );
+		$this->addToAssertionCount( 1 );
+	}
+
+	public function provideService() {
+		$wiring = require __DIR__ . '/../../includes/ServiceWiring.php';
+		foreach ( $wiring as $name => $_ ) {
+			yield $name => [ $name ];
+		}
+	}
+}