I have heard of some folks having issues on Apple Silicon builds of Premiere and After Effects, but the quickest thing to check is the Activity Monitor. Is any specific component maxing out? Are you playing the footage back from a slow drive? As you implied, ProRes Proxy should be incredibly light and easy to play back even on a very old computer. Are your proxies stored in a cloud syncing folder? I would try isolating the problem by working with a single proxy file in a new project. Can you play that back smoothly? If so, then we can try other troubleshooting steps.
Convert the full resolution footage to ProRes and skip proxies entirely. Make sure that the Sequence Video Previews are set to match the flavor of ProRes that you're using. So, if the camera original clips are transcoded to ProRes 422 HQ then set the Sequence Video Previews to Custom Quicktime ProRes 422 HQ as well.
The M1 Max should handle 8k ProRes playing from the internal Flash storage or Thunderbolt 4 SSD external storage very well.