I'm curious about the general effectiveness of the latest versions of GHC in optimizing single-threaded code. We know of huge gains with the parallelism libraries, but I'm wondering what the consensus is for code that's more inherently sequential.
Quite separately, runtime and library performance for some kinds of parallel programs is better.
Both sequential and parallel code got better, for different reasons.
That all happens before getting shunted off to LLVM, which in turn does a lot of block-level changes (which particularly affect numeric code).