Strange compilation behavior

[Simon Peyton-Jones]

| I'm using ghc 6.6.1 under Ubuntu Gutsy on a Pentium 4 machine, and I
| was working to get some code running in an acceptable time. I was
| surprised to find that turning on profiling switches made the code run
| over 40x faster!

That is indeed strange.  Things to try:

* Try without -O.
* Try with -O -fno-full-laziness.
* Add -dcore-lint (no perf effect, but does internal checks)
* Try with 6.8.1

Simon