[mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Andrew Coppin

Donald Bruce Stewart wrote:
    

Some things to remember using Doubles:

    * {-# OPTIONS -fexcess-precision #-} 
    * -fvia-C
    * -fbang-patterns
    * -optc-O2 -optc-mfpmath=sse -optc-msse2
    * -optc-march=pentium4
      

1. What do all those things do?
2. Is the effect actually that large?
    

Large? Depends what you mean by large, but adding a few flags to get
just a 10-20% speedup isn't to be ignored: