Fix the lags!
Whenever I precompose, split layer, or move the playhead one frame forward or backward, it takes three seconds from me pressing the hotkey to the command being carried out... and often precomposing will cause After Effects to crash.This happens regardless of if have hardware acceleration turned on or off. It feels like I am using AE on a computer from 10 years ago, even though my machine is overspecced for After Effects.
I have been through the Adobe Customer Care pipline (where's my purple heart?) and they have determined that it is not an issue on my end, but an issue with the software. So... fix it!