Unable to play high-frame compositions in realtime with M2 Max

I was able to play high framerate footage before with my 2019 macbook in the exact same setup with an external monitor. It's just impressive that a new 5k dollar macbook with a M2 is a downgrade in that regard…

as an addendum, I've been able to get slightly better playback by disabling MFR/GPU, and using one 1080p monitor. That seems to work by minimizing the time spent rendering UI, and maximize time spent on the next frame's loading from RAM, but it's VERY system-dependent. Perhaps increasing RAM speeds could help?

though I do the bulk of my work in CS6 now that version 23.whatevs is constantly crashing. It runs smoother anyway, and the new additions are just fixes for issues that creative suite cause in the first place. I can always use resolve to transcode to new standards.

After Effects is a program from 1994 or thereabouts. it's never been refactored or rewritten, so, as some might suggest, the only way to be happier here, is to lower your standards. I've never gotten my comps to render at realtime in any version post-CS6, and even then, I only managed it with 1080p, and GPU/MFR turned off. 

Note that adobe can't make the program multithreaded with their level of development, so they throw a single frame-rendering thread on each core. This means each core is separately accessing RAM, and each frame can only render as fast as a single core can do it. You may have spotted from time to time that a frame two to five ahead of the next renders before the next, causing hitching. This is why.

Even when it's playing from RAM, the rest of After effects is largely single-core, and the UI does not use GPU for the most part, so it's sharing its preview and file handling with the MASSIVE calculations needed to load and unload from RAM on the fly.