Exceptions actually have a huge performance hit, you should only use them in a HALT EVERYTHING IMMEDIATELY situations and never in anything that could be called repeatedly. We have refactored few of those to be 10-100 times faster by just returning success: false instead of throwing and catching exceptions.

After working few years on a complex web application, I am starting to feel this style. Doing RESTful APIs for anything else than dead simple CRUD is pain.