performance of monads

I see a lot of literature that says that monads "simulate" the effects of imperative programming concepts. It seems to me that the relative performance of monadic implementations must be equivalant to imperative ones to provide a strong case for functional programming. For example, in the Exception handling monad it seems that the "bind" function must be called continously to pass the Error value back to an error handling function. However, in imperative languages we can make an immediate non-local transfer of control. Similiar is the way State is handled. Do compilers for haskell do any sort of optimization on these monadic operations or is it all as ineffecient as it looks. Eric Wohlstadter UCDavis Software Tools Lab