Don't `sort` long lists
I'm looking at a ticky profile for the MultiLayerModules
test case and I'm noticing many calls to $l$smerge
from GHC.OldList
sticking out. They are probably due to sort
calls. We shouldn't be sorting lists (at least not over a certain length, say 10), it's rediculous to do so.
Instrument, detect and kill those calls.