As a test, I just did a comparison of a 5 Case Select and 5 IF equivalent in a 10mil pass FOR loop, both of which gave me an average of 16.5ms completion times.
This could just be the way my system handles them though and testing on your target platform will be the best way to determine the route to take.
Another thing to mention is to always use the most probable match for your Cases first to least probable. This can be help reduce the amount of checks it has to do if you know a certain value will be more common then others.

Another thing to mention is to always use the most probable match for your Cases first to least probable. This can be help reduce the amount of checks it has to do if you know a certain value will be more common then others.