Premier and Adobe used to be reliable

That's a miserable situation. And I've been there myself, of course. I think about everyone has, right?

But actually all of it sounds fixable. And perhaps some are inter-linked.

When it can't find your credentials, from seeing that happen over the years, I think it tends to be either a corrupt project or issues between Premiere and the OS and permissions. Sometimes using the CC Desktop app to uninstall Premeire, reboot, and then re-install Premiere has fixed that. Other times it did take staffer advice.

Posting both the full specs on your machines and all media used and effects can help us troubleshoot everything else.

Past that I would note, there are many million daily users of Premiere. Probably at least triple what it was a decade back. Something like that.

And yet there are far fewer posts here per day, on the days after update patches and releases, than we used to have. As a then-member of the community professionals, our private 'board' always included the "here we go again ..." comments with any release, as that would always be an "all hands on deck!" moment to handle the flood of posts.

Personally, I'm getting rock-stable performance with 25.2.1. Ryzen 3960x, 128GB/RAM, 2080Ti, running OS/programs on one Nvme, all cache files for Pr, Ae, Me, and Resolve on another Nvme. I work with BRAW, ProRes and general mov, some H.264, occasional Red and Arri clips, even a Sony or Panny here and there. Some Samsug phone media, and the occasional iPhone file sent to me. It's a mix of RAW, log, and Rec.709, and some of course HDR, though I tranform to 'wide gamut' working space sequences. And all Rec.709 outputs at this time.

Many other users are also getting good performance. But some, like you, clearly aren't. And need help or fixes for problems.

The staffers participating here have notified users about some replicated issues that will be fixed as soon as they can be assured they are putting out a clean build. How long? We never know, of course.