Bad behaviour in the generational GC with paraffins -O2
paraffinsL.hs seems to give a slowdown of almost a factor of 2 when using -O2 during compilation (also with -O).. I noticed that when tinkering with parallel variants, but happens even just for seq compilation. pL.hs is a cleaned-up, stand-alone version that triggers this behaviour.
I checked this with ghc-6.13 (HEAD as of 1.4.2010) and with ghc-6.12.2rc2 (as of 20.4.2010), with the commands below.
This is on a i386-unknown-linux machine