Thanks all of you! Really appreciate every response! It's so motivating.

@Mads
I beat the highscore by one point, by the way. persecutioncomplex
Hmm... I also noticed hi score with max integer value and your name by side.

How did you do that, what were your steps? I mean is it so easy and natural to insert fake score? Sure, I did nothing to prevent that, but there wasn't form like 'input your name and desired high score', anyway someone should at least know, what page to call. I read some threads here about this topic and all I understood, it is close to impossible to make 100% secure functionality. I really need your opinion.
@Grunnt
However, it stuttered a bit on my (admittedly not so recent) laptop. Perhaps it's generating a bit of "garbage"?
Tested on Celeron 1.4 single core old notebook with Win XP and there was less than 25% cpu usage and memory usage was like constant. So, how could I check whats wrong?