Perlin actually improved his original algorithm by creating the Simplex Noise http://en.wikipedia.org/wiki/Simplex_noise http://en.wikipedia.org/wiki/Simplex_no

Perlin actually improved his original algorithm by creating the Simplex Noise http://en.wikipedia.org/wiki/Simplex_noise http://en.wikipedia.org/wiki/Simplex_noise which runs much faster. As a matter of interest, Voronoi noise is also quite popular