LuaJIT (http://luajit.org/) performs quite well. While I can't say it'd be impossible, optimizing Python similarly would be much harder - Lua's tiny implementation and tendency to do everything in terms of a small and orthogonal group of concepts means it has far less that needs to be optimized. Python is pretty hairy in comparison.

Lua seems to have a similar advantage over Javascript, as well. LuaJIT beats Javascript V8 by a wide margin (http://shootout.alioth.debian.org/u64/benchmark.php?test=all...). It's not like Javascript implementers lack resources, either. LuaJIT is the work of one person.