Performance is a pretty broad term. There are many things you can measure or count and many ways to go about it. A profiler may or may not be able to not help you do that, depending on what it is exactly you're interested in.
Oracle ships the JDK with
JVisualVM, which allows you to monitor and profile things like CPU and heap usage. I've used that and, although it's pretty basic, for me it got the job done.
Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
