[Peaker]

Don't use "runhaskell", it's more of a "script mode".

Use: ghc -threaded -O2 main.hs && ./main

[payload]

There is no significant difference in this benchmark. Do you measure something different?

[Peaker]

I didn't measure, no.

I suppose maybe it uses the optimized compiled packages code, and the main code doesn't really do anything, so -O2 doesn't matter.

However, I would still expect "-threaded" to have an effect.

[payload]

Yes, a negative one for this benchmark :)