MAPI Developer: MAPI call (lpFolder)->OpenEntry() takes 2 minutes to open messages in mailbox

Recently I was working with a MAPI developer and came across this interesting issue. We noticed their custom MAPI application takes 2 minutes to open the messages in a given mailbox. Further troubleshooting we noticed they see this behavior with the MAPI call, (lpFolder)->OpenEntry(). It takes 2 minutes to open messages in a given mailbox…