I gotta echo everybody else that this game is very fun and could be really addicting, but the amount of enemies on-screen causes severe lag and it makes everything way too tedious. Even turning off the effects doesn't mitigate the lag very much.
Edit: If you guys want to do well, circle around the enemies with a slowdown or freezing powerup and wail at them with your bullets. Once you max out enemy slowdown, you'll literally dance around them like they're nothing (but be careful not to get trapped).
Edit 2: It crashed 19 minutes in on a really good run, so it's not particularly stable. Try the Steam version like the author recommended.