Here's a tip I've used in RPG campaigns where I – as the GM – expect to do a bunch of tricky rolling and don't want to slow things down: roll ahead of time.
Either with physicall dice or an Excel spreadsheet and a printer, it's super easy to come up with a ready-to-use list of rolls . . . dozens or hundreds, depending on how many you expect to use in the adventure. Do you suddenly need 20 killer robots to make 20 attacks? Just grab the next 20 entries on your list, and start the action faster.
This method isn't recommended for players, because the list of rolls (obviously) makes itself known ahead of time; the temptation is too great to try to manufacture situations to waste less optimal rolls – such as a critical failure on an impromptu "give that roadside goose an interesting name" roll. But it can be a great tool for the GM in certain circumstances.
-- Steven Marsh