Massive slowdown in mwc-random after switching to use of
simonpj at microsoft.com
Sun Jul 11 13:31:23 EDT 2010
| > caused a huge performance regression.
| You're using GHC 6.12.x presumably? There are known performance problems with
| using abstract PrimMonads in that version (and, actually, just using IO as
| The good news is that, last I checked, this isn't a problem in HEAD. The
| optimizer does better there somehow. The bad news is that 6.14 isn't out yet,
This is the first I've heard of this. Do you have a test case that shows up the problem? Then we can put it in the regression tests so it won't go wrong again.
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