Thanks for playing and for the constructive criticism! The waiting times was a known issue through later development, it was difficult trying to balance around making sure you can't beat the first two bosses way too quickly with fast recharges vs making the final boss way too hard with the slower recharges.
I had originally bounced around the idea of spawning more charges more quickly and requiring the player to get more of them before winning and maybe that would have helped your issue of the game being too slow. Sadly I didn't have the time to implement that change later in development and hoped that people would like the game regardless.
Thanks for being genuine in your critique, it helps me get better!