I'd like to know if the bad performance will ever be fixed or if Adobe just recommends different hardware, while other software makers get it done on the same hardware without a problem. In the last few minutes 2 other guys posted about the bad performance, so I'm not the only one.
Many users are running along fine in Premiere, some are having issues. Premiere has a massive user-base compared to any other NLE out there, and that's one of the joys of coding for it. It's used on such a wide array of kit. And of course, note that those who are working fine never come to a forum like this to post, but only those who are having troubles.
Sometimes issues are because of older kit or bad layout, such as too few drives for the app to run correctly. Some are for not having the right settings in the Project and Preferences panels for the machine or media in use. And of course there are issues as with any app for bugs and such.
I teach colorists how to work in Premiere for color, so I deal with people based in Resolve and Baselight daily. I work in Resolve also. On my 6-core machine, Resolve gets no better playback than Premiere. As with all other things, it depends on your machine and the setup within the app for how any one app will work. My Acer Predator Triton 500 laptop with a 2080 card does decently in Premiere, not so well with Resolve.
In this thread, now a FAQ for CPU/GPU settings on this forum, Andy does a good job of covering the proper settings for H.264/265 media ... and those vary depending on whether your CPU has Intel's QuickSync or not, and of course the capabilities of your GPU.
I use some of that, and a lot of BRAW, some RED and other media.