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Compiling with optimizations on hurts performance

The attached program runs many times slower when compiled with optimizations (4.5 seconds vs. 1.5 minutes on my machine).

I wasn't able to reduce the program to a small snippet so I attach the whole thing (including data files to process).

I compiled and ran like this:

ghc --make test2.hs time ./test2

And then

ghc --make test2 -fforce-recomp -O time ./test2

Trac metadata
Trac field Value
Version 6.10.4
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture
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