Thanks so much for playing and the great feedback!!! :D
Really great that you found and pointed about different bugs or features that went wrong. I have no idea what can cause some one of them such as the boss not spawning at the 5 minute mark and why the FPS drops when shooting. The shooting might be a problem with the browser version, but the timer for the boss makes no sense. I will have to do some serious debugging after the game jam.
I will go over all your points in detail after the game jam and try to make this in to my first "real" game.
I am going to play and rate your game before the jam ends!