What? There were pentium 2 and 3 machines back then that could certainly do more than a edge detection kernel every 2 seconds.
Or do you mean on an embedded CPU?
Software is iterative. At least when I was studying in the mid 90s people had really only just gotten the idea to do a Fourier transform of an image and look for high frequencies to indicate borders. Add ~3 decades of each generation of grad student doing slightly better than the last one.