its ok
this is definitely one of the better games factory 2 games ive seen lately, i do agree that it does, seem to hamper the experience with slight lag, you also have problems with random enemies disappearing into the abyss, i suggest in the future to use, flash for making flash games, no games factory :)
the art also needs improvement, it seems to be lacking and the black and white dont seem to engage the viewer too well. so you've got room for improvement.
i suggest you collaborate with someone next time on the art while you work your way through the coding and design....