Don't you want strong typing for better performance? That's what I thought, too. The VM designers say that in practice, type guarantees really don't help them n

Don't you want strong typing for better performance? That's what I thought, too. The VM designers say that in practice, type guarantees really don't help them nearly as much as you might think, because type checks are not a major drain on performance. No, but you can generate better code if you know exactly what types you're playing with ahead of time. Say you have a function like this: void foo(SomeClass obj) { obj.bar(); } That could be compiled to just a straight 'jmp SomeClass::bar', whether you're compiling natively or to a VM. If you don't have static types, the best code you can output is something along the lines of this: fn = lookup(obj, "bar") jmp fn Of course there are tricks that you can use to optimize this second case a bit that involve fancy static analysis, fancy JIT business, etc. but the point is that you will never generate better code than just a single jump to the right code, based on the types you know at compile time in a static language.