"Since network threat protection installed everytime a user access the web , sep will scan and it may slow down the operation"
=> please clarify which module is causing latency: Auto-protect or Network Threat Protection?
Can you confirm you have the same problem with Antivirus/Antispyware protection only? If you don't, it seems the problem comes from Firewall/IPS looking at inbound/outbound traffic. You may then add some Firewall rules to allow this specific traffic or IPS host exclusion to do not analyze this traffic at all (keep in mind this is lowering your security level).