I figured Johan is doing O2 for libraries and programs. I have done libraries at O2, programs at O1, which likely does explain the difference.

I'm still in a holding pattern in case there's also some other setting he's using.

Then I'll run both variations on the programs.

Thanks much.

I use "BuildFlavour = perf" for the compiler and otherwise don't specify any additional options (including to nofib), which I guess implies that the benchmarks are compiled with -O? Then I do

cd nofib
make clean && make boot && make -k 2>&1 | tee log1
make clean && make boot WithNofibHc=ghc-7.6.2 && make -k WithNofibHc=ghc-7.6.2 2>&1 | tee log2

nofib-analyse/nofib-analyse log1 log2

I followed the instructions at

http://hackage.haskell.org/trac/ghc/wiki/Building/RunningNoFib

If the defaults for nofib are wrong (e.g. if we want -O2 by default) we should tweak the settings so people get sensible results by default.