These applications are largely those that use heavy disk processing, and were often quickly ported to Mac OS X by their developers. Some application functions are actually faster in Classic than under Mac OS 9 on equivalent hardware, due to performance improvements in the newer operating system's device drivers. (This is likely a major reason why Classic is not supported on Intel-based Macs.) Motorola 68k code is handled by the same Motorola 68LC040 emulator that Mac OS 9 uses. Most of an application is run directly as PowerPC code.
Classic's performance is also generally acceptable, with a few exceptions.
