USoft BenchMark's Profiler provides hints about which database columns could be candidates for putting an index on. Obtaining these hints is useful for SQL statements that are executed because of constraints. Especially, of course, if they take up a lot of network time.
The Index Hints tab page
Generally speaking, indexes will increase the performance of your application. Performance, however, is a relative and subjective concept. For example: a badly written constraint may perform excellently on a small database or a fast machine. Therefore, concentrate your efforts on those performance aspects that are considered to be unacceptable.