I thought I remembered this being a service set to manual. We are running Exchange 2007 now so I could not check this. However <a href=”http://technet.microsoft.com/en-us/library/bb124644(EXCHG.65).aspx”>TechNet</a> identifies it as a manual service:
Microsoft Exchange Event (MSExchangeES)
Monitors folders and triggers events for server applications compatible with Exchange Server 5.5.
Microsoft Exchange Information Store
This is not supposed to be running at all times, but only when an event is triggered.