performance issues

i play skate. on steam and everything runs fine. but after 5-10 minutes i get 8-10 fps after having 100-150 fps. but also textures lag and turn black. a temporary fix is to validate the files on steam and it says "could not validate 3 files" and then those 3 files get reinstalled but same thing happenes after playing a couple of minutes. i've played during the testing phase and this issue never occured. i really want to play this game but it's impossible when it has these kinds of performance issues.

my specs: RTX 5060, Ryzen 5 7600 and 32 GB RAM