Thanks for the feedback!
1) WebGL is pretty slow, if it's an issue you can download it. I should probably compile to Linux and MacOS.
2) I added a lag time after to make hammering more deliberate, but you're right, I should consider lowering it. I'll do some tests. I can even make cooldown an upgradeable stat.
3) Difficulty would be a good idea! From playtests it seemed a little too difficult but I didn't want to make it too easy.