What is the relative performance difference of if/else versus switch statement in Java?

I remember reading that there are 2 kinds of Switch statements in Java bytecode. (I think it was in 'Java Performance Tuning' One is a very fast implementation which uses the switch statement's integer values to know the offset of the code to be executed. This would require all integers to be consecutive and in a well-defined range. I'm guessing that using all the values of an Enum would fall in that category too.

I agree with many other posters though... it may be premature to worry about this, unless this is very very hot code.