Some web pages load slowly, or a blank page loads when going through the ProxySG appliance (RFC 1323)
When RFC1323 is disabled, the ProxySG appliance will use a maximum window size of 65535 bytes. If a higher value was set with the tcp-ip window-size command, 65535 will continue to be used. Window scaling can only be used when RFC-1323 is enabled, so a window size greater than 65535 bytes would go against the standard.
The advantage of this RFC 1323 on the appliance is explained in Why should I enable RFC-1323? What are the advantages of enabling RFC-1323?
Also, sample troubleshooting steps related to RFC 1323 are illustrate in Troubleshooting web pages that do not load or load incompletely.