Cubase 11 Pro Video player freezing - settings

Hello there,

I am having a quite peculiar issue:
I was sketching a piano part for a film scene and wanted to import it into my template. Imported midi, tempo, video etc, all from the same files (so same video file). And while in my sketch file the video works perfectly smooth in my template file the video only plays a few frames and then freezes. I have both projects open side by side and the same issue occurs.
Video: H264, 1920x1080, 30 fps, 48KHz - 24 bit.
Windows PC
Tempo map imported from other cubase file, midi imported from Dorico.

My template does have a lot more tracks and pre-determined routing, but when I play the video from the new cubase session none of the cpu-meters spike. Which leads me to believe that I just missed a setting somewhere.
If anyone could help that would be very welcome!