Question Why does the CPU use a lot when I work with Bolt?

My processor is i5-7300.If only unity is opened, only 30% at most.What happened to cause this?That's make no sence.Thank you for your replies.

 

Because bolt is cpu intensive. And a % doesn't mean it's a lot. 50% of a small bit of processing is tiny if nothing is being used.

Look for numbers not %

 

you can also profile the editor, maybe can see what is slowing it down:
https://docs.unity3d.com/Manual/ProfilerWindow.html