Gwern Branwen wrote:

FWIW, I was actually discussing compilation with -O2 on 6.8 with Sjannssen and he told me that even with -O2 turned on, GHC now defaults to -fasm instead of -fvia-c.

Ah. Yeah, that could well make a big difference... (Especially on a machine with insufficient RAM.)

Also, the release notes are talking about the runtime speed of binaries, not compilation.

But since GHC is compiled with GHC, you would expect a (small) speedup of GHC. (And indeed that is what the release notes specifically suggest.) Either way, I (and probably a number of other people) will go test what speed difference it actually makes to compiled code. ;-) (I've been wondering for a while now whether there's much to choose between -fasm and -fvia-c.)