Hello, My Outlook is running with 100% CPU load since the upgrade to Big Sur. Every now and then the load goes down for a short time, then up again. No synchronization errors are displayed, the status does not hang either. Load is so high even in offline mode After a new start of Outlook it behaves quietly for a few minutes, then the load goes up. Now and then the load goes to below 10% for 2-5 minutes, then stable again to full load. Current versions are macOS: Big Sur 11.3.1 Microsoft Outlook for Mac: 16.48 The computer and therefore the Outlook are completely fresh installed. I have tried various tips from the Microsoft Community Forum: Do not show messages in conversations Privacy - disable optional connected experiences incl. telemetry data ... Workaround: The other installed programs are manageable. Microsoft Office and Teams, OpenVPN, Firefox, Kaspersky Internet Security. While troubleshooting, I noticed: Quit Kaspersky Endpoint Security - problem gone. After a new start of Kaspersky it takes a few minutes again, then the CPU Load is high again. Kaspersky Endpoint Security for Mac (11.1.0.210a) Database up to date Real-time protection enabled Encrypted traffic scanning not allowed (turning this on makes no difference) Unfortunately, there are no more settings here. Now I have BigSur as the changed factor, Kaspersky as the culprit, but Outlook with the high processor load. Can anyone help me further here? How can I continue to troubleshoot this? Greetings Hansaplast