NFA demonstrates poor performance when Symantec Endpoint is installed on NFA servers including:
All versions of NFA.
Symantec Endpoint operates at the System Kernel level which mean that even just excluding specific directories or disabling services does not help NFA performance.
We have not seen this issue with other anti-virus programs to date, when they are set to exclude C:\Windows\Temp and <install_path> and all its subdirectories as documented in the NFA documentation.
Completely uninstall the Symantec Endpoint software from all NFA servers and reboot each server.
This should result in major performance improvements with your NFA environment so long as your systems meet the current specifications in the NFA Documentation.