I recently removed the Network Threat Protection component from the Symantec Endpoint Protection installation on all of the servers and desktops on a customer network.  Here is a list of things that happened as a result:

• Backup throughput increased by 50% (using Symantec Backup Exec 11d)
• Exchange backups stopped failing due to the remote agent becoming disconnected
• Performance of SQL-based applications improved
• Group Policy processing time at desktop startup decreased
• LDAP search query times for the Exchange server improved (System Center Essentials was raising alarms for these taking over 6000ms sustained for 5 minutes, with the alarm threshold being 100ms)
• RPC latency for the Exchange server improved (SCE was raising alarms for average latency being over 70ms sustained for 5 minutes)
• Office applications opening files on network shares became more responsive
• Desktops stopped rebooting randomly throughout the day

Seriously, what a piece of junk.