Actually, I would probably bet that SML with MLton is the fastest (in some benchmarks) by a fairly large margin, but I can't find any up to date benchmarks.

Haskell is usually about 1-10x slower than C for the same task, while MLton has actually outperformed C in some benchmarks.

Edit: My information is out of date -- dons is almost certainly right on this one. I'd go with his estimation.