Thanks for your help !
My laptop is connected to a Barco E2 system with 1080p@50Hz EDID. This is a setup we're using daily in corporate events since as the broadcast cameras run at 50Hz in France, every element in the video chain is based on this 25 (or 50) images / second basis...
The fps while offline is 60fps when I'm playing a generator and 50fps when I'm playing my 50fps test movie. GL time is around 0.3ms and CPU 0.0ms
When I go online the fps moves between 49fps and 50fps when playing generators and is almost fix at 50fps when playing my test movie. GL time is a bit lower, around 0.1ms, and CPU is still around 0ms
I notice that when switching from one media to another in the same quad, the fps transitions between the media's (or generator's) fps to the output's 50fps.
If it can help, here are my test files : https://www.dropbox.com/sh/x23w9doscizf ... XHGLa?dl=0
(Diagonal motion with black and white stripes rendered at 25, 30, 50 and 60 fps)