I would be cautious of overfeeding as well to promote growth as this would certainly lead to a decline in your parameters or potential for secondary pesties to visit (planaria, scuds, hydra, etc)
I would like to second what jinkz said...They don't eat nearly as much as you might want to feed them. Even my large army of cherries only gets like 2 algae wafers every other day.
The only way I know to increase the metabolic rate of shrimp is to increase the water temperature of their tank. However, this will also shorten their life span. The same is true of snails (higher temp, faster growth, dead sooner).
I highly recommend not taking any action, and let nature take it's course. You'll be wondering what to do with all of your shrimp in no time.