Speed Doubler

Speed Doubler was a utility software package that was co-developed by Connectix and MindVision Software for Macintosh computers from Apple Computer. A Japanese version was released on floppy disk by Seiwa Systems.

Features
The Speed Doubler control panel includes 3 major features. The first two support Motorola 68030 and 68040 processors, but a PowerPC processor is recommended to full advantage of all the features:
 * Faster File Copying replaces the Macintosh Finder's copy functionality with a more efficient, multithreaded version that allowed simultaneous copies before a similar feature appeared on Mac OS 8.
 * Faster Disk Performance replaces the Macintosh system software's Disk Cache routine with a version that is up to 40% faster for slower drives.
 * Faster Emulation replaces the original Mac 68k emulator by Gary Davidian with a much faster dynamic recompiler for Power Macintosh computers. Because System 7.x still contained a lot of 68K code that needed to be emulated, Speed Doubler's dynamic recompiler can double the speed of a Power Macintosh 6100.

Version history
Speed Doubler was first released by Connectix at Macworld Expo Boston in August 1995 and supported System 7.0 to 7.5.x. Versions 2.0, 1.3.1, and earlier have known issues with Mac OS 7.6 and are disabled by Mac OS 7.6.1. Version 2.0.3 and earlier do not work with Mac OS 8, but 1.3.2 does. The last major release, Speed Doubler 8, was introduced in 1997 and works with Mac OS 7.5.5 to 8.0; various updates added support up to Mac OS 8.6. Updates are limited to features and compatibility; there is no noticeable improvement in emulation performance between versions. The effect of emulation was also decreased as Mac OS 8.6 had introduced a PowerPC-native nanokernel that had been rewritten by René A. Vega.

Mac OS 9 or later is not supported, as Apple had by then improved disk caching and also implemented its own dynamic recompiler by Eric Traut. The Faster File Copying component of Speed Doubler was spun off into a stand-alone utility called Copy Agent.