There is a masterwork potion belt in the FRCS that lets you draw one as a free action each round. If you had one in each hand, that would be up to 3 per round. If you can apply the rule from TWF that drawing two weapons takes as much effort as one if you have the feat, then that would be 4 per round.
Above that, I'm not sure without resorting to extra action shenanigens (or taking Quick Draw...).