XDA Developers found a way to dramatically improve your SD Card speed, by only applying a simple cab tweak. Note: this tweak applies only to devices sporting a physical SD/miniSD/microSD slot, so no Internal Storage like HTC Touch Diamond.
Applying the supplied cab will change some registry entries in your device (changes which are reversible by simply uninstalling the cab) that will make your Windows Mobile Professional 6.1 Operating System take advantage of Direct Memory Access and improved File System Caches. It's not magic, the potential has always been there, but so far unused on stock devices. Your memory card will not perform faster but your system will take advantage of its (close to) real speed.
We've benchmarked tnyynt SD TuneUp on an HTC Touch HD, with a Sandisk Class 6 8GB microSD Card (the one supplied with the device, to be more specific), using SKTools benchmark option for Storage Card Read, Storage Card Write and Storage Card File List, just to come up with the conclusion that installing this tweak will at least double your file system access for Storage Card (red bars), which is useful for accessing files stored on it, let it be file operations like copy/move or basic everyday usage like media playback.