diff --git a/lib/IMAP/Threading/ThreadBuilder.php b/lib/IMAP/Threading/ThreadBuilder.php
index 15012c6ac6..ae5f906685 100644
--- a/lib/IMAP/Threading/ThreadBuilder.php
+++ b/lib/IMAP/Threading/ThreadBuilder.php
@@ -25,32 +25,48 @@
 
 namespace OCA\Mail\IMAP\Threading;
 
+use OCA\Mail\Support\PerformanceLogger;
 use function array_key_exists;
 use function count;
 
 class ThreadBuilder {
 
+	/** @var PerformanceLogger */
+	private $performanceLogger;
+
+	public function __construct(PerformanceLogger $performanceLogger) {
+		$this->performanceLogger = $performanceLogger;
+	}
+
 	/**
 	 * @param Message[] $messages
 	 *
 	 * @return Container[]
 	 */
 	public function build(array $messages): array {
+		$log = $this->performanceLogger->start('Threading ' . count($messages) . ' messages');
+
 		// Step 1
 		$idTable = $this->buildIdTable($messages);
+		$log->step('build ID table');
 
 		// Step 2
 		$rootContainer = $this->buildRootContainer($idTable);
+		$log->step('build root container');
 
 		// Step 3
 		unset($idTable);
+		$log->step('free ID table');
 
 		// Step 4
 		$this->pruneContainers($rootContainer);
+		$log->step('prune containers');
 
 		// Step 5
 		$this->groupBySubject($rootContainer);
+		$log->step('group by subject');
 
+		$log->end();
 		// Return the children with reset numeric keys
 		return array_values($rootContainer->getChildren());
 	}
diff --git a/tests/Unit/IMAP/Threading/ThreadBuilderTest.php b/tests/Unit/IMAP/Threading/ThreadBuilderTest.php
index 649600b450..87189ed029 100644
--- a/tests/Unit/IMAP/Threading/ThreadBuilderTest.php
+++ b/tests/Unit/IMAP/Threading/ThreadBuilderTest.php
@@ -29,17 +29,25 @@
 use OCA\Mail\IMAP\Threading\Container;
 use OCA\Mail\IMAP\Threading\Message;
 use OCA\Mail\IMAP\Threading\ThreadBuilder;
-use function array_values;
+use OCA\Mail\Support\PerformanceLogger;
+use PHPUnit\Framework\MockObject\MockObject;
 
 class ThreadBuilderTest extends TestCase {
 
+	/** @var PerformanceLogger|MockObject */
+	private $performanceLogger;
+
 	/** @var ThreadBuilder */
 	private $builder;
 
 	protected function setUp(): void {
 		parent::setUp();
 
-		$this->builder = new ThreadBuilder();
+		$this->performanceLogger = $this->createMock(PerformanceLogger::class);
+
+		$this->builder = new ThreadBuilder(
+			$this->performanceLogger
+		);
 	}
 
 	/**