Simple performance improvement ideas

[ensisoft]

• Use a different container for entities that are interested in input events. So instead of having to iterate over all entities simply iterate over some "input enabled entities"
• Maybe squash Lua BeginLoop/EndLoop and Update functionality into a single function and loop over the entities once.
• Dispatch game and physics events in a bulk virtual call (i.e. reduce virtual function calls)
• Remove OpenAL error checking code (likely very unoptimized in Emscripten)