Each execution of the script on a Web page increases the amount of memory under QtWebEngineProcess. This continues until QtWebEngineProcess not eat all the computer's memory. I created 20 classes inherited from QMainWindow with QWebEngineView. Then I repeatedly send a command to all classes: view-> page () -> runJavaScript (command) every 100 ms from QTimer. And I see how infinitely QtWebEngineProcess eats memory. "command" inside the JavaScript performs blank function especially for test.