CSNW constantly resolves printer names, server names, and object properties. The more clients that connect, the more activity.

Upgrade to Service Pack 6 (SP6).

Use Regedt32 to navigate to:

HKEY_LOCAL_MACHINE\SYSTEMCurrentControlSet\Services\NwRdr\Parameters

Tune the following values:

 Value   Type   Dflt   Min.   Max.   D e s c r i p t i o n 
 NdsObjectCacheSize   REG_DWORD   0x0   0x0   0x80   The number of resources to cache. Set it to the number you are connecting to. 
 NdsObjectCacheTimeout   REG_DWORD   0xa   0x0   0x250   The number of seconds an entry is valid for. Set it based upon how often the resource can change.