i love it whenever people being reasonable - appreciate it, sir.
I didn't even expect "sudden changes", i just wanted to voice my personal view of things - but as it seems, my thoughts were not only mine XD.
About the memory usage: it happened to us too. We didn't even know that RenPy internally converts all images into RGBA bitmaps

.
I man: who could even guess that a 300 kb render could end up with 8 MB in RAM? Normally, that's still no issue, if you use 1 render to show, maybe 2 on screen (1 as overlay). But as soon as you work with sprites, or if you use different assets on different parts of the screen at once, it might easy end into a RAM-mess.
It still can have different other reason, but if i would have to bet on one of them, this one would be my choice #1