Abysmal Performance 24.0

Here is a diagnostics tool Adobe made. Try this.
 https://helpx.adobe.com/premiere-pro/kb/fix-premiere-pro-crash-issues.html

If you are using a lot of Motiongraphics templates in the project this could do it as well. I've had a lot of issues with those.

Sometimes updating drives fixes the issue as well. 

Is your SSD close to being full? This could cause slow playback as well. It could also be that there is more footage than normal. If you have edited 60g of footage previously and it was fine, then now editing more like 500g. This is just more data to go through for the computer. if that is the case. 

ProRes files are larger, so I'm not surprised the playback is slow. This may be something with the new update, but I would proxy the footage anyway. 

You should always proxy so that these situations don't occur. 

Other things to check would be the sequence setting to see if the frame rate matches the footage.

Bottlenecks are some what tricky to diagnose without having the machine in front of me, but from what I'm reading, proxying the footage would be your best bet as of right now. Do it on Apple Pro Res Proxy if you end up doing it. 

I haven't noticed this issue with the 24. Maybe someone from Adobe will comment about what in the program could be causing this. 

I've NEVER had to proxy HD footage until this upgrade.  All clips are ProPres and I'm editing on an SSD.

Hope* lol 

Are you playing your media off of a slow hard drive? ie.) a large HHD. Switching it to a fast SSD will help a lot. 

I would recommend proxying your footage before editing. This will solve the problem.

Also, HVEC "H.265"  codec footage is very tough to edit. If that is what your file type is, then transcode it to a more editing friendly codec such as Apple ProRes. 

You can just proxy your footage and it should edit just fine. Just toggle on your proxy button. 

without more information such as where the media is stored, or what type of file it is I can't really do much but give suggestions. 

Bope this helps!