The same also happens to me with Black Magic. The game used to run fine even on my old potato PC, but after a certain point in the story it starts lagging terribly.
Only games that do this are Black Magic and Ripples.
Let's see in the next update. May or may not be an optimization issue, if so, perhaps it'll be fixed then.
I have a very high grade pc one that's just a step below the ultimate pc I haven't seen this issue pop up for me in the slightest but i understand where you are coming from in the sense that it does lag because i have similar issues with other renpy games that have been fully completed as of recently, so that being said i do believe it might just be an issue with newer versions of renpy's software.
Renpy isn't the best at playing videos, and it uses software decoding instead of hardware like a normal video player like VLC. So the CPU usage is really high while they're playing in the game. And it seems like the newest version of Renpy made that usage go up a little bit more. The game plays fine on my system but I have heard this issue from a couple of people so I understand.
