Well, It's a multi-threaded program, and when you create a project it will start out by indexing everything. So while it's doing that, it can spend quite a lot of CPU time -- "top" etc. typically show the CPU time spent by all the threads in a process, so you can easily see it go up to N * 100% based on your cores.

That can get occasionally annoying, if you drop in a a bunch of 1mb text files in your repository and it insists of examining them.

But, introspection and refactoring capabilities are great.

Does it stay there all the time? CPU going above 100% during indexing and inspections is normal; we use multiple cores to complete the operations faster.