[Melanogaster]

Yeah, it was psicomaniaco. I'll quote him again on that:

Ok, here's a hint: when you get to the screen change area (the one where the music stop playing), OPEN THE MENU BEFORE GOING TO THE NEW SCREEN.

If the game freezes when oppening the menu, wait some seconds, and the game will un-freeze. Now, close the menu and go to the new area.

If you do this, the game will NEVER freeze when going to a new area. Oh, and do this before going to a boss fight, and after you beat the boss.

Again: OPEN THE MENU, WAIT FOR THE MENU SCREEN TO APPEAR, CLOSE THE MENU, GO TO THE NEW AREA.