named stops responding on zone transfers

[Federico Bockel]

Im having problems when named refresh the zones, the service stop
responding for some minutes, i have 3000+ zones.
I added tranfers-in and transfers-out to limit the # of zones transfered
at the same time on master and slaves.
Is it common that when slaves are refreshing zones they stop respondig
for some minutes?(master continues responding ok)
What can i do to solve this?
Any idea if the transfers-in and transfers-out will help?
Thanks
 
    Federico Bockel