Sample of the CoCo 3 erasing 727 pixels and drawing another 727 pixels per frame using under 60% CPU usage.
For some details about how this was done see my blog entry:
https://nowhereman999.wordpress.com/2021/12/18/coco-3-3d-pixel-animation-and-how-to-see-how-much-cpu-usage-is-being-used-per-frame/