@JelleZijlstra discovered something interesting yesterday: bytecode compile times on main are currently quadratic in the number of local variables (3.11 is still linear). For example, a function with 100,000 assignments to unique local variables takes well over a minute to compile (but is less than 2 seconds on 3.11).

I believe the culprit is the new LOAD_FAST/LOAD_FAST_CHECK stuff. The current implementation appears to loop over every local variable, and for each one, loop over all bytecode instructions. This can probably be refactored to run in one pass for all locals.

CC: @markshannon @sweeneyde