Look man I'm not trying to defend Howard here or imply you're tech illiterate, or that all your issues clear up 100%, but have you by chance updated your driver's? Mine were out of date enough starfield threw up a warning which I ignored and was not having a good experience with the same as you(iunno your ram or storage config but I was running on an average NVME and 32 gigs ram with 5600x and 6700xt). But after I updated a lot of the issues smoothed out, not all, but most. At 60 fps average with a mix of med high at 1080p though. Maybe worth a try?

I'm on a 5700xt and game runs around 60 fps at 1080p everything cranked and no FSR or resolution scale applied, so I'd say either your drivers are out of date or something else is wrong there imo