Yes, that 10% is an average over seven benchmarks. The numerical one gets a 25% speedup, the one with a bunch of exceptions doesn't benefit at all. The funny

Yes, that 10% is an average over seven benchmarks. The numerical one gets a 25% speedup, the one with a bunch of exceptions doesn't benefit at all. The funny thing is, if you're interested in performance, you're probably going to be writing a JIT, so this optimization is really just a stop-gap measure. In fact, the inline threading I mentioned is a kind of cheap JIT: it copies the in-memory executable code from the instructions at these goto labels to form basic blocks in an executable CFG. That gets you 1.6x speedup on those benchmarks, but it's a lot more work.