diff --git a/src/Repository/UserRepository.php b/src/Repository/UserRepository.php
index 30bf4b0a..5834ce69 100644
--- a/src/Repository/UserRepository.php
+++ b/src/Repository/UserRepository.php
@@ -71,6 +71,21 @@ public function getAllUsers(): array
 		return $this->toEntities(get_users());
 	}
 
+	/** @return array<int> */
+	public function getUserIdsBatch(int $number, int $offset): array
+	{
+		return array_map(
+			'intval',
+			get_users([
+				'fields' => 'ID',
+				'number' => $number,
+				'offset' => $offset,
+				'orderby' => 'ID',
+				'order' => 'ASC',
+			]),
+		);
+	}
+
 	/** @return array<User> */
 	public function getAllMemberUsers(): array
 	{
diff --git a/src/Service/MembershipService.php b/src/Service/MembershipService.php
index 13e61f17..a677146a 100644
--- a/src/Service/MembershipService.php
+++ b/src/Service/MembershipService.php
@@ -368,11 +368,18 @@ private function extendSectionsDates(int $userId): void
 
 	public function timeUnlockLevelsForAllUsers(): void
 	{
-		$users = $this->userRepository->getAllUsers();
+		$batchSize = 100;
+		$offset = 0;
 
-		foreach ($users as $user) {
-			$this->timeUnlockLevelsForUser($user->getId());
-		}
+		do {
+			$userIds = $this->userRepository->getUserIdsBatch($batchSize, $offset);
+
+			foreach ($userIds as $userId) {
+				$this->timeUnlockLevelsForUser($userId);
+			}
+
+			$offset += count($userIds);
+		} while (count($userIds) === $batchSize);
 	}
 
 	public function timeUnlockLevelsForUser(int $userId): void
diff --git a/tests/access_logic_tests.php b/tests/access_logic_tests.php
index 1b4bf2a9..cd3e10ad 100644
--- a/tests/access_logic_tests.php
+++ b/tests/access_logic_tests.php
@@ -233,6 +233,47 @@ public function getActiveWithAccessByUserId(int $userId): array
 	}
 }
 
+final class BatchedUserRepository extends UserRepository
+{
+	/** @var array<array{int, int}> */
+	public array $calls = [];
+
+	public function __construct(private int $userCount)
+	{
+	}
+
+	public function getUserIdsBatch(int $number, int $offset): array
+	{
+		$this->calls[] = [$number, $offset];
+
+		if ($offset >= $this->userCount) {
+			return [];
+		}
+
+		return range(
+			$offset + 1,
+			min($offset + $number, $this->userCount),
+		);
+	}
+}
+
+final class BatchedMembershipService extends MembershipService
+{
+	/** @var array<int> */
+	public array $processedUserIds = [];
+
+	public function __construct(UserRepository $userRepository)
+	{
+		$property = new ReflectionProperty(MembershipService::class, 'userRepository');
+		$property->setValue($this, $userRepository);
+	}
+
+	public function timeUnlockLevelsForUser(int $userId): void
+	{
+		$this->processedUserIds[] = $userId;
+	}
+}
+
 final class LoginLevelRepository extends LevelRepository
 {
 	public function __construct(private MemberLevel $level)
@@ -431,4 +472,19 @@ function createUnlockController(
 	assertSameValue(null, $capturingService->savedMembership, 'Denied button unlock must not save a membership.');
 }
 
+$batchedUserRepository = new BatchedUserRepository(205);
+$batchedMembershipService = new BatchedMembershipService($batchedUserRepository);
+$batchedMembershipService->timeUnlockLevelsForAllUsers();
+
+assertSameValue(
+	[[100, 0], [100, 100], [100, 200]],
+	$batchedUserRepository->calls,
+	'Users must be loaded in batches of 100.',
+);
+assertSameValue(
+	range(1, 205),
+	$batchedMembershipService->processedUserIds,
+	'Every user must be processed exactly once.',
+);
+
 echo "Access logic tests passed.\n";