Five minutes is a long time not to be able to find something in the books. I can see it taking that long every once in a while, but really two minutes is usually all it takes.
If I am reasonably certain something will come up during a game that I'm sketchy on, then I'll make notes before-hand. For example, I ran an owlbear recently and hadn't done much with grappling, so I wrote down all the steps just so I would be sure to run Improved Grab correctly. Or, if a seldom used condition is involved, I'll write down all the effects of said condition in the description. I guess in this case it helps that I don't use random encounters.
If a player brings something up, and I don't know how it works, we can find it pretty fast. I at least know where to look things up in the book fairly quickly, and the index, while not perfect, is a nice quick resource. I peruse the Rules forum a lot, and that helps tremendously for those things that rarely come up but are confusing when they do, so that helps as well.
If for some reason we can't find something after five minutes, and it does happen occasionally, then we'll go with an educated guess, write down the problem, and find how its supposed to work after the game with everyone knowing that if the rules are different, then it won't run the same next time. Usually doing such in the players' favor if possible. When this happens, we usually find that we've guessed right anyway.