Cameron Brown

Hi all, I'm starting to explore moons around Jool, the only issue i'm having is my speed as I enter the system. I'll encounter jool and then adjust my manouver until I encounter one of the moons. The problem is my speed is like 5000ms and I end up having to use about 3000 delta V to slow down and orbit. How can i encounter another planet or moon without coming in so quickly? I feel like i'm doing something wrong.