queries run on the database, client side CPU shouldn't be an issue unless you mean the application itself is lagging, becoming unresponsive
Are you running low on disk space?
How much memory have you assigned to your JVM?
How much CPU is 'high?'
How long do you leave the app open? How many connections do you have open? How many code editors do you have open?
Are you using the Welcome Screen/Instance Viewer/Real Time SQL Monitor? Those are Java FX screens and will use your GPU if you have one.