CPU usage is high when you use RPC over HTTP protocol in Windows 8.1 or Windows Server 2012 R2

Consider the following scenario that takes Microsoft Exchange Server 2013 as an example:

  • The Mailbox server role is enabled in Exchange Server 2013.
  • Exchange mailboxes use extended MAPI to communicate with the Exchange Server.
  • The extended MAPI uses Microsoft RPC over HTTP (remote procedure call over HTTP) protocol.
  • Many clients (such as mobile devices) are dropping connections to the Exchange Server.

In this scenario, the CPU usage on the Exchange server may reach 100 percent.\

Hotfix: https://support.microsoft.com/en-us/hotfix/kbhotfix?kbnum=3041832&kbln=en-US