diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 469a23773d..69bcec2bd8 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -10,6 +10,7 @@ Yii Framework 2 Change Log
 - Bug #19927: Fixed `console\controllers\MessageController` when saving translations to database: fixed FK error when adding new string and language at the same time, checking/regenerating all missing messages and dropping messages for unused languages (atrandafir)
 - Bug #20002: Fixed superfluous query on HEAD request in serializer (xicond)
 - Enh #12743: Added new methods `BaseActiveRecord::loadRelations()` and `BaseActiveRecord::loadRelationsFor()` to eager load related models for existing primary model instances (PowerGamer1)
+- Enh #20030: Improve performance of handling `ErrorHandler::$memoryReserveSize` (antonshevelev, rob006)
 
 2.0.49.2 October 12, 2023
 -------------------------
diff --git a/framework/base/ErrorHandler.php b/framework/base/ErrorHandler.php
index 81a20f0a3c..393438ede5 100644
--- a/framework/base/ErrorHandler.php
+++ b/framework/base/ErrorHandler.php
@@ -94,7 +94,7 @@ abstract class ErrorHandler extends Component
                 set_error_handler([$this, 'handleError']);
             }
             if ($this->memoryReserveSize > 0) {
-                $this->_memoryReserve = str_pad('', $this->memoryReserveSize, 'x');
+                $this->_memoryReserve = str_repeat('x', $this->memoryReserveSize);
             }
             // to restore working directory in shutdown handler
             if (PHP_SAPI !== 'cli') {