Users experience delays in web browsing. ICAP scanning is configured on the ProxySG or Advanced Secure Gateway (ASG).
Slow scanning is the most likely caused by Content Analysis attempting to virus scan infinite streams. Infinite streams are connections which deliver ongoing streams of data to the client such as a stock ticker web application or online music or video streaming service. To avoid this problem, Symantec recommends enabling deferred scanning.
To enable deferred scanning, you edit the ICAP service.
Log in to the ProxySG or ASG Management Console
Edit the ICAP service.
Select Configuration > Content Analysis > ICAP > ICAP Services
Select the ICAP service
Click Edit. The Edit ICAP Service window opens
Enable scanning deferral
Select Defer scanning at threshold to enable the defer scanning feature
Enter a value (0-100) to set the threshold at which the ProxySG or ASG defers the oldest ICAP connection that has not yet received a full object. For example, if the maximum connections are set to 100 and you set the defer threshold to 65 percent, then up to 65 connections are allowed before the ProxySG or ASG begins to defer connections that have not finished downloading a complete object.
Click OK to close the Edit ICAP Service window
To learn how deferred scanning works, see this article: How does deferred scanning work?