I don't know which Lua you're used to, but as of 5.1, it's incredibly fast; I may be benchmarking the wrong things (the big one I tried was finding the first 2,000,000 primes by trial division, which should lend itself well to hotspot optimizations). Either way, though, I'd still argue that a VM (JVM and Lua were just a couple of examples of VMs that are fast, used in real applications, and are readily jailable) is the ideal solution.