"It's fast," said one developer source of Mac OS X running on Intel's Pentium processors. "Faster than [Mac OS X] on my Dual 2GHz Power Mac G5." In addition to booting Windows XP at blazing speeds, the included version of Mac OS X for Intel takes "as little as 10 seconds" to boot to the Desktop from when the Apple logo first displays on screen.
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"Taking a universal binary and timing its startup in Intel native speed versus its startup when opened via Rosetta results in a slowdown, but not as much as one would think," said another source. "The apps run at about 65 to 70 percent of their normal speed."

However, some PowerPC-native applications realize little to no speed reductions while running under Rosetta. A source told AppleInsider the current PowerPC version of the popular Firefox web browser loads just as fast under Mac OS X Intel as it does on a high-end dual processor Power Mac G5.