AnimationTimer is fired once per "planned" frame (i. e. running at maximum possible FPS), not per "actually rendered" frame. JavaFX contains a lot of optimizations. For example, a boolean property animated over time to switch from false to true will only imply a single modification, hence only one frame is actually rendered. -Markus
-----Original Message----- From: openjfx-dev [mailto:openjfx-dev-boun...@openjdk.java.net] On Behalf Of Michael Paus Sent: Donnerstag, 22. Dezember 2016 17:29 To: openjfx-dev@openjdk.java.net Subject: AnimationTimer and actual frame rate Hi all, for quite a while now I am observing a strange behavior when running some JavaFX graphics tests. The scenario is very simple. I am running some animation which puts some load onto the graphics engine and I am trying to measure the frame rate via an instance of an AnimationTimer. When I increase the load high enough I reach a point where the indicated frame rate is just 60FPS or even a bit lower but the observed frame rate on screen has already dropped to something like 1-2 FPS. So what I observe is that the AnimationTimer is running much faster than the updates of the graphics. How can that be? Does anybody have an explanation under which circumstances this can happen? Or is this behavior a bug which I should report? Just some puzzle for the boring Christmas holidays :-) Merry Christmas to all of you Michael PS: My system is a MacBook Pro with NVidia graphic card.