I may have found the trouble. I had an 8gb microSD card installed. I was planning on swapping that out with a 32gb one from the wife's now replaced Droid3. When I put the 8gb card in a PC it seemed to have a lot of trouble reading it. Eventually the card just died. I'm guessing the D4 was likewise having trouble with the card and that might have contributed to the problem. Meanwhile with the 32gb card it seems to be performing properly (or at least I'm now used to the slow-down).
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