Hello everyone

I am new to linux, I have installed arcolinux (arch based distro) that I was testing in a virtualbox and using Kdenlive. All worked fine.
Now I have decided to buy a new computer and installed same distro. I have a AMD 3970X with a Nvidia 2080Ti and cannot play a simple 2 seconds PNG sequence.
A mov file plays smoothly (could be better) a mp4 file laggs in the first 3 seconds then plays smoothly (more or less)
Whats is wrong with my system? Do I have to install something else? cps test
Why was this working fine in a virtual machine before, with a system far inferior (2013 Imac) than this new one?
Help please.

Thank you