I do not believe it is a case, maybe you do not notice the issue. The link with the provided train and city panning - can you make it full screen and check if there are fluency disruptions (like lags) on city panning scene?
Lags seem to be inevitable in Qubes OS even in 480p for such dynamic scenes due to X11 and Xen software limitations (it’s not CPU/RAM/Hardware problem), it was discussed on github tracker. I hope migration to wayland will fix it someday.