> mainbus0 (root): SUNW,SPARCstation-10
> cpu0 at mainbus0: TMS390Z50 v1 @ 33 MHz, on-chip FPU
> 
> does it mean cpu is 33MHz ???

I guess it does.

> Seems a very poor CPU.

The SS10 was produced between 1992 and 1994 -- it's an old system as they
go. The CPU could be upgraded with various third party options (the 
Ross HyperSPARC upgrade, f'rinstance) but the base configuration had a
33MHz SuperSPARC (there were CPU modules for the SS10 running at up to
50MHz, according to the Sun hardware guide at..
http://sunsolve.sun.com/handbook_pub/Systems/SS10/SS10.html )

It's only a poor CPU if you're thinking in terms of PC clocks.

m.