Power64 is very fast without sacrificing compatibility. It runs at full speed on any Power Macintosh computer, even with sound support! It also allows you to instantiate multiple Commodore processes simultaneously, so you could theoretically be playing two games at once (yes, it's a dubious feature). Power64 is currently one of the most complete Commodore 64 emulators around.
ReSID 0.13, which provides enhanced sound emulation. Many of these emulators have since been ported to Macintosh, and several Macintosh-only emulators have proven to be high-quality emulators as well. The Commodore 64's popularity has resulted in a number of emulators for PCs, Amigas and X Windows.
