If perf is important, I'm surprised you're using Love2d and not just using C++ with SDL and Box2d directly. Afaik Love2d just uses vanilla Lua (and not LuaJIT) which, while faster than similar languages, is still pretty wasteful of cycles when high perf is needed.
perf is important but I also want user scriptability (as part of the actual app feature(s)). Love2d uses LuaJIT (it does use the C API to bind its native calls rather than the FFI -- but actually that has better perf when not JIT'ing).
