Reimporting project just using a small part of processor

I am reimporting the project and i see all applications of the computer just use 12% of processor, and max 12% of ssd and around 40% of memory, it is taking hours to complete and dont understand why just dont use 100% of processor and finnish this sooner

 

If reimporting is a single thread operation, and you have an 8 core processor (or 4 core with HT) and it was maxing out its core or thread, you'd see about 12% total processor usage.

 

Yes, that is what i thought, Unity is not using all cores, i read it uses it for Unity editor