You have already discussed in the User's Guide the the advantage of uncompressed over compressed image files, but I would like to know more. Sure, it takes extra processing to decompress compressed files for display. But the smaller compressed files also take less time to read from the disk. In a case where disk I/O is the bottleneck (i.e., disk I/O is slow, processing is fast), won't the reduction in disk I/O more than make up for the increased processing load, making compressed image files like .jpg & .gif faster? Ultimately, real data from actual time tests would settle this, perhaps you have already done this and can report the answer.
Thanks as always,
-- David McFarlane, Professional Faultfinder