Comment by FabianCarbonara

Python never touches the PPU: the memory-mapped registers live entirely behind a thin C layer (_snesfb / _snesstage modules). Sprite/tile bitmap data gets packed into VRAM tile banks once at startup; at runtime Python only mutates shadow state (hardware tilemaps, an OAM shadow, a framebuf for the GUI stuff) and once per frame the C side DMAs the dirty buffers across during vblank.