Yup, no trick there. If the selection moves to the other character, the
original background behind the raised top and left edges has to be
blitted back to VRAM, which means that it also has to be stored
somewhere. TH04 backs up exactly the two 256×8 and 8×244 strips behind
Reimu and Marisa, requiring 2 KB of heap memory, whereas TH05 simply
gave up, and backs up the entire 640×400 screen, totalling 128 KB.
Part of P0125, funded by [Anonymous].
nmlgc