squid throughput limits?

[Wojciech Puchar <wojtek@xxxxxxxxxxxxxxxxxx>]

i recently installed squid on P4 machine with FreeBSD, serving about 1000 
users with diskd, 3 spool dirs etc. etc. and it uses 30% CPU at max load 
hours.

disk load is less than 30%.

is it possible to run squid for caching >3000 people network (will be >90% 
CPU)? squid can't divide for many processors/cores.

and wy so much CPU power?