Hi, I'm playing this game on a Mac Mini by using this: getwhisky dot app to do that.
There's a bit where after the first battle with Vampy, that right after Lasca says something when Simone is attacked by another magical girl's powerful attack, the game slows to a crawl - the characters move very slowly compared to the normal cutscene speed.
And the text boxes slow down too - it takes longer to have the text boxes open and close, even on the menu of the game where you can choose episodes . You also can see a number on the side of the screen (it wasn't always the same number). I'm not sure if it's meant to be the magic gauge or not, but I think so at least sometimes?
I had downloaded the latest version of the game and put the save files from the game I was playing (which is the second most recent version) in the latest version in the hopes it'd fix this, but it didn't.
I figure, but could be wrong, that it's the animation of the attack by the other magical girl that causes that at a certain point, or how the screen becomes white and remains that way for a long time - although Lasca saying something after the screen goes white appears normally, and then the game starts to slow down to a crawl afterwards.