I remember fractal zooms in real time on the Amiga 500 and they were using a trick: they'd only recompute a few horizontal and vertical lines at each frame, wit

I remember fractal zooms in real time on the Amiga 500 and they were using a trick: they'd only recompute a few horizontal and vertical lines at each frame, with most of the screen just being a copy/blit of the previous frame, shifted. After a few frames all the pixels from n frames back were discarded. This was a nice optimization and the resulting animation was still looking nice. Good memories.