This corresponds to what I've seen, you'd expect that Office 2008 being a native Intel application would be much faster than Office 2004 which is PowerPC and runs in emulation on Intel. Well, the results are a little confusing. It is faster, but not much in many things:
| | Excel Open | Word Scroll | Entourage Download |
| 2004 | 0:25sec | 1:04 sec. | 1:29 sec |
| 2008 | 0:23 sec | 0:51 sec. | 0:49 sec |
So don't upgrade to Office 2008 for speed. Also there is a new SP1 which is supposed to fix some of the many stability issues on Office 2008. Good luck. I think I'm staying on 2004 for now.