By default, the GHC system emits all possible not-too-expensive runtime checking code. If you are brave or experimenting, you might want to turn off some of this (not recommended):
-dno-black-holing won't buy you much (even if it works) -dno-updates you're crazy if you do this -dno-stk-stubbing omit stack stubbing (NOT DONE YET)
Warning: all very lightly tested, if at all...