On Sat, Feb 2, 2013 at 3:19 PM, Nick Rudnick
Roughly, I would say the differences in runtime can reach a factor as much as 1:10 at many times -- and so I am curious whether this subject has already been observed or even better discussed elsewhere. I have spoken to somebody, and our only plausible conclusion was that software like web browsers is able to somewhat aggressively claim system resources higher in the privilege hierarchy (cache?? register??), so that they are not available to other programs any more.
Maybe the Haskell program requires a lot of disk IO? That could easily lead to a big performance change since disk is so slow compared to everything else these days. You could try looking with 'lsof' to see if the browser has a ton of files open or try running the Haskell program with higher or lower disk IO priority via 'ionice'. -- gwern http://www.gwern.net