This refers to the Shared Insight Cache (SIC)
The Symantec Endpoint Protection Security Virtual Appliance is a Linux-based
virtual appliance that you install on a VMware ESX/ESXi server. The Security
Virtual Appliance integrates with VMware’s vShield Endpoint. The Shared Insight
Cache runs in the appliance and lets Windows-based Guest Virtual Machines
(GVMs) share scan results. Identical files are trusted and therefore skipped across
all of the GVMs on the ESX/ESXi host. Shared Insight Cache improves full scan
performance by reducing disk I/O and CPU usage.
Check the attached admin guide starting on Chapter 29 for full details