diff --git a/rector.php b/rector.php
index 7cf424f73e88..b1520c38e10a 100644
--- a/rector.php
+++ b/rector.php
@@ -59,7 +59,7 @@
         PHPUnitSetList::PHPUNIT_100,
     ]);
 
-    $rectorConfig->parallel(120);
+    $rectorConfig->parallel(120, 8, 15);
 
     // paths to refactor; solid alternative to CLI arguments
     $rectorConfig->paths([__DIR__ . '/app', __DIR__ . '/system', __DIR__ . '/tests', __DIR__ . '/utils']);