Cant figure out my issue with 5-6k videos

Melaix

Headset: Valve Index
OS: Win7
GPU: 2080

Getting lag even with 80hz settings and is unplayable at 144hz for 5k-6k videos. Some videos will not play over 2888p and moves to the next video.

I have tried downloading LAV and swapped to CUVID and done a lot of other changes that are found within this forum and still cant find out the reason behind it. Local VR files run perfectly.

Supersampling at 1.0x, SteamVR settings both at 100% resolution although it suggests 150% (cant play at that setting, too laggy)

Any fixes or questions please let me know... dont want to waste up my premium :

Melaix

I tried both and usually h265 works best and sometimes runs 2880p videos but never anything over that. My cpu and gpu usage are usually around 40-50% when a video is running. DirectShow if you are referring to the toggle within SLR, then yes I tried turning it off as well.