If you're playing a system with lots and lots of rules, than expect the game to come to a screeching halt when you need to interpret the many rules you don't intimately know. Like say, Grapple. Which is going to come up a lot given how many monsters use grapple. Or when a player uses something that causes a condition, but no one at the table remembers what that condition does (Shaken, Nauseated, etc).
This is what I'd do.If you're having trouble with players having to stop to look up a spell, make it a rule that they must have the book open to the spell they want to cast *before* their turn.