I'd need an old system to test that on. Though I wouldn't call it stressful; it's mostly just hoping that the raw picture resource fits into memory so it can be rendered into the static screen buffers. The raw resource can then be freed. All that just means the bigger the picture resource (the more commands), the longer it'll take to render.
If my fantasy computer (which runs a 68020 at 16 MHz) can render the SQ3 robot freighter pilot screen (8.43 KB) in less than three seconds using only C code... I would bet actual money that the cave entrance, the new and pretty version, could fit in less than 10 KB if you properly hand-traced it just for the dithering, and render on the same order of magnitude on an old system.
Also, *undue.
