Both V8 and LuaJIT are extremely impressive but I'm not sure either dominates the other, at least when I last benchmarked things <http://tratt.net/laurie/research/pubs/files/metatracing_vms/... (the benchmark suite is on github, so you can update/rerun). To cut a long story short, each has some benchmarks where it blows the other out of the water, but overall I'd say that, from a performance perspective, it seems to be a score draw.