Thank you all for this usefull post. I have a qml game, I'm using a Timer that is triggered with a bool variable that is binded to keys pressed and release, at a fixed speed of 1000/60.
The animation looks smooth in some cases in but in other cases it does not. So the correct aproach should be not to use a Timer, but trigger the animations with vsync, right? Is it possible to do this in qml? Also it seems qml does not 'respect' the timer interval, sometimes I get higher frame rates, maybe I have something else mess up. Besides Timers, I am using NumberAnimations, I think that will mess the Timer interval ? I have done some testings using Timers, and qml render.stats, in my laptop with a Nvidia GTX1050 TI, I get:

windows with native screen, animations are ok, smooth, renderstats shows aprox. 60fps windows with gaming monitor of 165Hz, animations are not smooth, renderstats shows aprox. 77fps linux mint, native screen, animations are ok, smooth, renderstats shows aprox. 60fps linux mint, gaming monitor of 165Hz, animations are ok, smooth, renderstats shows aprox. 120fps macbook air, native screen, animations are ok, smooth, renderstats shows aprox. 60fps macbook air, gaming monitor, animations not smooth, renderstats shows aprox. 45fps, maybe because of the hdmi cable with a display port adapter, that mess the performance iPhone 7, animations are ok, smooth, renderstats shows aprox. 60fps android phone, animations are ok, smooth, renderstats shows aprox. 60fps
Is there any cross plataform way of checking the vsinc and triger it to render the game loop ?
By the way, I have builds of my game for Windows, Mac, Linux (only binary) here https://drive.google.com/drive/folders/1JWrkcLyNfIZSmleJOJRkunM8mZUiIxDG?usp=sharing
also the code, if anybody wants to check it https://bitbucket.org/joaodeusmorgado/davidgalacticadventures/src/master/
Thanks
printescreen.png

I'd like to bump this topic, it's been over 5 years and you'd think small sprites would be better respected and not blurry with the qt engine (as ya know, sprites came from the pixel era) , I've tried everything under the sun to get sprites that aren't blurry and it seems you have to basically use an AnimatedImage or your own sprite engine to make do.

I would have modified the sprites item or made my own copy but I couldn't find a copy of its source