There are three fixes in MP3 related to GUP's.
SMC.exe process consumes excessive virtual memory
Fix ID: 2137535
Symptom: A Symantec Endpoint Protection client acting as a GUP may leak virtual memory.
Solution: Symantec Endpoint Protection was modified to properly clean up an object that was not being destroyed when the client is a GUP.
GUP does not respond immediately to client requests when policy contains GUPs in different subnet
Fix ID: 2143552
Symptom: Clients do not immediately contact the nearest GUP when policy is applied containing a GUP in a different subnet. The client does not download from the GUP until the threshold has passed "Maximum time that clients try to download updates from a GUP before Symantec Endpoint Protection Manager".
Solution: The GUP is now considered ready for connections if the GUPLIST that includes the static GUP is not empty.
GUPs request incorrect delta package from server
Fix ID: 2202771
Symptom: One client comes online after being off-line for some time. The client requests a delta from its GUP covering the off-line time span. All other GUPs on the same subnet incorrectly request the same delta from the server.
Solution: Microsoft changed the default receive timeout in Internet Explorer 7 from 3600 seconds to 30 seconds. This may cause client connections to be cancelled before the GUP can finish downloading the content from Symantec Endpoint Protection Manager. This results in the client switching to the next GUP. Symantec Endpoint Protection was modified to properly apply the correct timeout to the connection handle.
http://www.symantec.com/business/support/index?page=content&id=TECH103087&locale=en_US