Speed of RAW/JPEG writing limited by SD card speed - increasing CPU speed does not help.
While what you say is of course true, we do see a huge speed difference between cameras using the SAME cards. How do you explain this? Perhaps the CPU /SD subsystem is doing more work than we think within the DIGIC?
For example, the DIGIC might not be using DMA controlled buffer but instead is feeding the card by itself.
big RAM buffer to keep more images in memory
If we're on the subject... I would guess some cameras have a few MBs lying around (especially if we do not use SuperFine JPEGs). Do you think it is possible to create a small (1-3 JPEG) buffer in memory to be used by CHDK?
This will make the recycle to next shot (as well as short burst) much faster (as long as RAW is disabled).
mkmenuts