I've been having a problem with a power user in Outlook 2019. When the user exits Outlook 2019 it stays in memory and consumes 20-30% CPU in the background and does not exit for at least 20-30 minutes. Eventually it exits from memory as well.

I've done the following to troubleshoot this problem, but I haven't found a solution to it yet.

  • Disable all add-ins.

  • Repair OST file using SCANPST tool.

  • Removed all mailboxes from Outlook profile except for the default one.

  • Recreated Outlook profile.

  • Recreated the user profile.

The user is a power user, so he has more than one mailbox attached to his Outlook from Exchange Server. There's nothing fancy in the configuration either.

This happens to his profile whether he is logged in on his desktop or his laptop. The ost size is approximately 50GB, but even after recreating his profile many times with limited accounts his Outlook always keeps running in the background.

  • 1
    If you create a test mailbox for the user, does the same behavior happen, a single 50 GB file is reaching the upper limits of Outlook. Did this problem recently happen? Are you able to revert back to a previous build of Outlook when it didn't happen? Are you able to only attach a few of their mailboxes to prevent the behavior? Edit your question instead of submitting a comment to include this vital and required information necessary to answer your question – Ramhound Apr 3 '19 at 11:05
  • I used a different test account on the same user's computer and it seemed to have worked just fine, so I guess the mailbox size is causing the problem. – Aasim Apr 15 '19 at 9:04

When you exit Outlook, please also check Task Manager to see if Outlook still runs?

Agree with Ramhound, 50GB is a large size. According to this article, the recommenced size would be around 10GB. Please archive your mailbox to see if there are any improvements.

I checked several similar threads in Technet fourm:

Outlook causing high CPU usage

Outlook 2010 High CPU usage

This issue could be related with some background service. We can try opening Outlook in safe mode to see if the issue continues. Please exit Outlook, press Win key + R to open the Run command, type outlook.exe /safe and then press Enter. This helps eliminate whether the problem lies on any third party add-ins.

  • Sorry for the delay in responding, I've tried outlook safe mode still facing the same issue even in safe mode – Aasim Apr 15 '19 at 8:55
  • I think if other software interact with Outlook. we can temporarily close antivirus programs on this PC to see the results. – Perry Apr 17 '19 at 6:37
  • I made an error in stating the size was 50Gb, i just verified and its only 30 Gb. Do you still think the cause is due to size? How can we be 100% sure of that? Also why is there a lot of activity when we close Outlook program, In Task Manager Outlook.exe keeps consuming 20-25% CPU continuously after closing the app, whether we have add-ins enabled or disabled – Aasim Apr 19 '19 at 6:28
  • I checked this on my side. If I exit Outlook, it should not list in the Proesses. If you still see Outlook running, we can right click it and choose End Task. Will it help? – Perry Apr 22 '19 at 5:29

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