Statically vs dynamically typed peformance difference is clear for virtually any static or dynamic language you care to name, it has nothing to do with the jvm being "tuned" for a language:
http://shootout.alioth.debian.org/
The LuaJIT performance is pretty impressive for a dynamically typed language, but it's hard to deny the fact that mainstream dynamically typed languages our outperformed by their static counterparts.
Thats partly because they were not designed for performance. Lua of course was as it was designed partly for slow small systems. But pypy is getting on pretty well too and javascript, showing what you can do even if not designed for performance.
You pretty much have to enforce static type invariants (e.g. "this variable will never be other than an int") to JIT stuff performantly. I don't think that's a point against the GP's argument at all.
