Yeah. All three of the things you've mentioned are dependent on the speed of the card. Read speed for startup and navigation and write speed on switching as it has to write everything in it's buffer to the drive. Usually the read speed for all but the worst cards is more than most consumer cameras can handle.

Faster cards can't hurt but you don't need to spend mega bucks on some ultra super expensive turbo card. I've got a bunch of budget CF cards and I've never had any trouble. My IXUS 300 has enough shutter lag caused by the autofocus system anyway