Every 12 mins the Server Service will announce itself to the Master Browser on each protocol installed. If having a 1000 clients doing this on two protocols like the TCPIP- and Netbios-protocol, then it will lead to 10000 packets/hour.

One can stop this announcement / broadcasting by adding this DWORD value in the registry:

[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \LanmanServer \Parameters]
Hidden = 1

One can also configure the machine not to show on the network using command line:

net config server /hidden:yes

Note it may take up to half an hour before being removed from the browser list and become invisible in the Network Neighborhood/My Network Places.

Related Make your network shares hidden

More Info MS KB265284
More Info MS KB314498