Screen capture slows down after a while... why?

[sblantipodi]

I asked it on the mailing list but since no one answered I try it here, someone with a similar problem could chime in.

I'm using GStreamer Java to capture the screen on Windows 11 with an Nvidia GPU.

I have noticed that from time to time the capture framerate slows down a bit, let's say from 60FPS to 45FPS
even if my PC is pretty in idle...

Highering the capture framerate to 144FPS increases the problem and the slow down is bigger to 70FPS or lower.

My app is a JavaFX one and it runs with a system tray icon.

If I open a window, for example the settings of my app and leave this windows opened in foreground,
the slow down does not happen...

Is it Windows that forces the app on idle?
Is it my CPUs that pushes the thread on the ecore?
I have a 13900K CPU, even ecores should be powerfull enough for the task.
Is it a GStreamer problem?

What can it be? Any ideas on a possible solution to the problem?

Thanks
Davide