I've been using Tweaks2k2 ...
There's a couple of tweaks in there that tend to have a positive effect on WM5 - This can be done using a mix of registry hacks and other utilities, but Tweaks2k2 has them all built in. These are just a few of my favorites... not all affect the speed, but they make the device more friendly...
- The ability to change the soft keys at the bottom of the screen (IMHO the best tweak there is).
- The ability to change the system font (all versions of WM)
- Alarm fix for WM2k3/WM5 - this is a fix for the alarm wake time, seems to help if you use scheduled backups
- File based registry
- Optimized cache - up to 20% increase in speed
- The ability to change the Top and Bottom bar colors....