TidBITS has posted an article on troubleshooting techniques that anyone can use.
Although specialized knowledge certainly helps, troubleshooting is a universal skill. If you can figure out why your brakes are squeaking or why the sewing machine is jamming, you can figure out computer-related problems. Despite what many non-computer people think, there's no real difference.
“Feanor” adds a comment to Slava’s Mach-O ABI post:
Case in point: the _msgSend routine of ObjC is in /usr/lib/libobjc so every message sent in any piece of ObjC code has that 11 cycle penalty tacked onto the beginning, and then it gets the 9 cycle PIC penalty once you actually get there... every object function (method) call in ObjC goes through that.
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iTunes recompiled by GCC/MachO was 30% slower at MP3 decompression than with CodeWarrior/PEF. Lame MP3 Encoder was 50% faster with CodeWarrior PEF than with GCC/MachO, both on OS X. (both are Carbon apps)
