limit cpu usage by replication process

[y3by]

hi ppl,

I've created a db and defined replication with more than 30 MSDE on a VPN.
the db is in a double PIII XEON with 1.5 gb memory
every thing works fine but when ever i update more than 30000 records... then machine starts replication and the processor goes up to 100%...

until replication finishes the machine is very slow..
querys take to much time...

can i limite the process of replication to 50% of the processor machine?!
can i define that only one processor deals with replication letting the other to other querys ?!

any help would be apreciated!!