true, but not the whole picture
In order of increasing speed:
When Apple drops Yonah and puts Merom in the MacIntels, they'll start at #2, and can move to #3 and #4 in the future.
(The #3 is minor for most apps, and comes from the fact that even though application code and libraries are running 32-bit, calls to the operating system support APIs are 64-bit. If you do a lot of I/O or memory calls, the 64-bit OS can help your 32-bit application. This is how Windows x64 does it, the OSx64 implementation is unknown)
That's true, but 32-bit code on the 64-bit platform runs faster than 32-bit code on the 32-bit platform !!ehurtley said:(i.e. 32-bit code on the 64-bit platform runs slower than 64-bit code on the 64-bit platform, even if the core app doesn't really NEED to be 64-bit.)
In order of increasing speed:
- 32-bit app, 32-bit OS, 32-bit chip (today, Yonah)
- 32-bit app/OS, 64-bit chip (June Woodcrest, August Merom - Merom in 32-bit 25% faster than Yonah)
- 32-bit app, 64-bit OS/chip (XP in June/August, wait for WWDC for news about true 64-bit OSx64)
- 64-bit app/OS/chip (the future, but few apps today for Windows, none for OSx64)
When Apple drops Yonah and puts Merom in the MacIntels, they'll start at #2, and can move to #3 and #4 in the future.
(The #3 is minor for most apps, and comes from the fact that even though application code and libraries are running 32-bit, calls to the operating system support APIs are 64-bit. If you do a lot of I/O or memory calls, the 64-bit OS can help your 32-bit application. This is how Windows x64 does it, the OSx64 implementation is unknown)