[Samba] PDC emulator overloaded

[blizzards at libero.it]

Hello all,

i'm using samba + winbind yo connect to AD win 2003 on many linux box.
I use winbind to retrive users and groups list quering PDC emulator.
When PDC get many requests (i use squid with ntml transparent auth + winbind 
also) it get overloaded and slow down reply to my servers.
The problem is that when this situation occur, all services stop to work, and 
the users (10.000) became very angry.
How can i solve this problem?
I know that there was only i PDC on network, so can i build a dedicate samba 
server to act as PDC or BDC or other to help real PDC emulator to load the 
share?
Someone can give me advices?
Thank you.