So
To add to this, I understood what happened with some issues, is that majority of devs create an H scenes as a common events aka a separate entities for easy access and trigger and not overwork the game, what happened here is that majority of scenes are in fact NOT common events but instead as auto run IF and switches conditions are met which it can work until it doesn't which happened in kana and Jack First sex, due dumping all events into a single map AND event blocks it overlapped and it always default to that Alice scene.
The reason for the lag in some places despite killing the density and wheather effects is due the ridiculous amount of paralalel events running/trigering at the same time. Like the guest room/inn room/alice home maps, it has over 30-65 events running at the same time, majority being empty events which despite being empty it eats up most of your allocated memory and so it lags really bad.
Why the gallery doesn't unlock all? Well at first I thought it was because it was forgotten to add them to the switch list but actually it wasn't after adding them as i soon learned that the scenes dont exist so they were there as placeholders, copy paste Common events that will fade to black and done. As in the full events like the ntr door and nts sex, but just a small thing was done in those and it was actually hard to find those events and went to carefully check line by line and those scenes are incomplete despite having the videos and pictures.
And for paradise Island for those who don't know because i can't remember if people actually had access, well the map is in the game but you can only access it when you control sayako, and I cant remember when that happens. Anyway, when you get control of sayako you have to go to the massage parlor and move to another room and interact with the paintings on the right where you will enter paradiseisland although the scenes are just a single line and done.