Probably, building an optimized stage1, skip building stage2 and get nofib to be compiled with the stage1 compiler. I'm not sure off the top of my head how to do the last step. Edward Excerpts from David Feuer's message of 2014-08-19 03:21:49 +0100:

I'd like to try out a bunch of little changes to the list stuff in base and get some nofib results for each change. Is there a way to do this without recompiling all of GHC each time?