2.53 sculpting mode CPU multiple core usage?

I am using Blender 2.53 64 bit, window 7, AMD Phenom II X4 920, 8GB Ram
The thread option whether checked or not, the CPU usage also is about 30%.

Is it normal situation now?

There is a threaded sculpt option in user preference, or sculpt tool section.
I think it is in latest builds. I haven’t got a multi core computer, so can’t verify how good this is.