[Haskell-cafe] Interesting effect of upgrading GHC

Hi guys. I just removed GHC 6.6.1 and installed 6.8.1, and I noticed something rather unexpected. I recompiled an existing program (with -O2), and instead of taking 30 seconds to compile, it took roughly 2 seconds. That's a really serious speedup! o_O Anybody have any idea what might have caused this? (Not, you understand, that I'm complaining! But the release notes say 10-15% faster, not 15,000% faster...) I am also curiose to see whether the compiled code execution speed is better/worse - but the program in question is mainly GUI, so I can't test it with that... Perhaps my Chaos program? ;-)