FarmerTed in our forums has found a great writeup by Pocketnow.com on how to increase the speed of your storage card. It was Developed by our friends over at XDA.
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.
Click on the image to get a bigger view of the results and head over to Pocketnow to read more about it and download the cab. If you give the cab a try, post about your findings in our forums.