Performance of Lumetri in After Effects 22.3.0 (and the beta) is extremely slow. Not sure if this is specific to M1 processor or not. The problem is occurring specifcially with H.265 / HEVC footage. I *think* this is a new problem.
Spec 4k @ 23.976, 4:2:0 footage.
In Premiere, this takes 0 render time.
In After Effects, it takes a full second to render a frame.
Running the same type of adjustments in Colorista renders the frame in 19ms. That is more accurate behavior.
To make sure this has nothing to do with a bugged .cube file, this is all that's being adjusted in the Lumetri FX: