I have to say that the performance of the game is more than acceptable.
How it could be improved:
Fullscreen, no chrome [window borders]
Mouse capture / hide / replace cursor
Custom icon on windowed game [not the HTML5 logo]
Leaner exe with separate data files
Cruft removal from exe [unused icons and cursors]
And that would be just about the only criticisms. I don't know if these are inherent compiler or designer issues. Maybe a combination of both ;)
If these issues are forced through the codebase... maybe someone, more clever than I, would see fit to contribute to (or fork) the project to address some of these points.
Thanks, JohnnySheffield, for making your experiment available for us to scrutinize.