Thank you for playing our game and for your detailed analysis!
Regarding autosaves and the "back" button, we deliberately chose to omit them. When a game has more complex mechanics and animations, these features become a near-endless source of bugs and issues with the Ren'Py engine.
As for optimization, you're right. We haven't fully figured out the best way to optimize most things yet. This is also compounded by the fact that we targeted an increased resolution of 2640 x 1440 (instead of standard Full HD) from the start, aiming for better quality