A few ideas that works for some:
1) To go along with players preparing their actions ahead of time, roll both attack and damage dice at the same time. If the attack misses, the damage can be ignored but if successful the player doesn't have to waste a few extra seconds hunting down the appropriate die and giving it a spin.
2) Have the DM keep easily readable notes on important PC stats in front of them (such as AC and Defense numbers and other important abilities). This saves the DM the time of having to constantly ask a player what their numbers are and can keep NPC actions flowing quickly.
3) Resist the temptation to crack open a book mid-action. If you forget whether Circumstance A grants a +1 or a +2 bonus, make a quick judgement call and move on. Maybe even ask an inactive player to look it up while you continue on so that you'll know the answer next time it comes up but don't stop the game to wait for somebody to clarify the rule or you'll really slow down the action and end up with similar slow-downs in the future.
HARRY DRESDEN — WIZARD
Lost items found. Paranormal Investigations.
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