If I understand correctly (correct me if I am wrong) , in order to assign a specific update rate to view , it should :

1) Set QGraphicsView update module to NoViewportUpdate
2) Connect a timer's timeout signal to QGraphicsScene::update() slot

However, I have a question about the above behaviour. I think QGraphicsScene::update() would update every items on scene , no matter the region/rect is changed or not. Am I correct? Is it possible to update only the changed region/rect like what BoundingRectViewportUpdate mode do?