"Rob Galbraith":http://www.robgalbraith.com/bins/multi_page.asp?cid=6007-7699 did actual in camera testing with the Digital Rebel XT to see what were the fastest cards. For most of these, the RAW write speed wwas the most affect with the Sandisk Extreme III 1GB and 2GB having identical performance at 4.888MBps write JPEG and 6.26MBps RAW.
It is also interesting to see the 4GB cards were slightly slow at 4.56MBps JPEG write and 5.611 MBps with the SanDisk Ultra II 4GB where the cluster size of 4KB seemd a whisker faster than 32KB clusters.
It was also interseting to see that basically SanDisk and Lexar comes out on top at least in these tests.
Many companies sell CompactFlash media; relatively few actually design and manufacture the key internal components, including the controller and flash memory. This column lists the source of the key component or components inside the card, to help you determine if cards with different labels on the front are in fact similar or identical under the hood. For example: as of this writing, all the cards of a given capacity in this database that use Toshiba SLC components are effectively the same product. In most instances, the company marketing the card is purchasing assembled Toshiba CompactFlash cards, then placing their own label on them (this practice is common in the memory industry as a whole). Therefore, determining which company's Toshiba SLC product to buy should be done based on your examination of things like warranty, tech support and the reputation of the company selling the card.