Heh, this ended up being a much longer answer than I expected.
At the time, I was using a 7 year old 980ti which had seen pretty much daily use during those years, so I'm honestly surprised it was still working at all. It was very very unstable to the point where I'd be having the entire PC crash up to 8 times an hour (Depending on what I was doing). Somehow I managed to set up that scene without it crashing, but it was late in the day, and I figured I'd come back to it the next day or whatever. However, after that the longest I was ever able to actually have the scene loaded was about 3 minutes before it would crash. Realistically, I probably could have actually done the renders, but it would have taken like 20 times longer than normal, so instead of delaying the update I just said fuck it and drew some stick people. Another fun fact about the 980ti is that it was the original reason that there aren't a whole lot of students at the academy. Since I could have a max of like 3 characters on screen at once without it crashing, trying to populate backgrounds and things was basically impossible without photoshopping every render, so I rewrote that part of the game to make the lack of students part of the story. This is also why there are strange shadow people in the lecture hall when Kellin is introducing himself and stuff. I'd planned to fill out backgrounds with those instead of actual characters, but it turns out they're almost just as bad for performance, so I dropped the idea after that. I still need to get around to going back to rerender that bit without the random shadow people, but I'm in no huge rush on that front.
These days, due to the generous support of those enjoying the game, I have a better GPU. Specifically, it was actually just one guy who straight up bought me a new one by buying the game for some silly amount with the agreement that I'd use it to buy the GPU, so now I have a 3060 instead. This, in addition to someone else doing something similar allowing me to get 64GB of RAM, has allowed me to start sometimes filling out backgrounds with the second year girls, which a lot of people mistake as me just adding more characters because I think that's what people want. The reality of that is that they're just the background characters I would have added if I'd had a better GPU from the start, but I decided to give them a little bit of personality at least because I kinda dislike the idea of actual background characters. At very least, I felt they should have names. I also figured I might as well use them occasionally for stupid scenes that would derail the main girls' stories if I were to have them involved instead. (Like the ghost dildo thing, which would clash pretty heavily with the story of any of the main girls who aren't already aware of MC's power)
I could definitely get that MS paint scene finished now though, but given how frequently I get comments asking me not to change it, it's not very high on my priority list. HS2 is quite poorly optimised though, so I can say that whilst 8GB of VRAM would be fine most of the time, a scene with 5 or so characters might start to struggle depending on the map. It kinda depends, but either way the main point is that you could probably have a 4090 and still run into issues in HS2 a lot sooner than you'd assume based on the GPU.