howdydoody Yeah you should not be having issues with that setup. Is it when you're trying to play h265 (aka HEVC) files?
I'm assuming so since that's usually the case, so if you haven't done the below already you'll likely need to
1.) go to the Microsoft Store and download the HEVC codec. Used to be free though now it costs $0.99, but just search reddit and a link to a second free version has been posted a few times on r/oculusnsfw
2.) likely need to make sure you have the k-lite codec pack installed
The above are specifically for helping to smoothly play h265 files (which is what virtually any 6k video will be). If you do the above and are still having issues with stuttering, try another VR player (I'm assuming you're using Deo). For example HereSphere is a solid player with a free demo version available on Steam, among a number of other free ones you could try.