CPU use goes up and down

Hello to all.
I was searching the mailing list and I could'n get any information about this 
strange behavior.

I'm using the latest squid 2.5 stable 2 compiled with 8192 filedescriptors,
I'm using a partition of 19G for a 15G cache with reiserfs loaded as module,
I have 450MB RAM, 2 SCSI 10.000 RPM SCSI Disks, and a PIII procesor.
My Linyx is a RedHat 7.3 Linux with the standard kernel.

I'm fine with file descriptors now and the cache is growing fast.. as is 
spected with nearly 1000 clients a day.
The cache goes really well, the only thing that I really don't like that much 
is that the processor goes 
from 20% to 99% of use in random slices of time.

I don't know if someone has had the same problem or can give me a hand.
I feel like is something with the filedescriptors, or maybe having raiserfs as 
module, but I really rather to know first if someone have has the same problem 
cuz' the server is in production now.

I have a test machine but don't present this behavior cuz' it doesn't have the 
same charge.

Thanks in advance for the help

Fernando J. Andrade P.
Pontificia Universidad Católica del Ecuador
Dirección Informática
Servicios Informáticos
Quito - Ecuador