Outlook add-ins can slow down the application and cause delays when you start the program or switch between views. The Slow and Disabled Add-ins report in Outlook shows which add-ins take the longest to load and which ones have been automatically disabled due to performance problems. This article explains how to open the report, interpret the load time data, and decide whether to disable or remove a slow add-in.
Key Takeaways: Reading the Slow and Disabled Add-ins Report
- File > Options > Add-ins > Slow and Disabled Add-ins: Opens the report that lists add-in load times and disabled status.
- Load time column in seconds: Shows how long each add-in took to load during the last Outlook session.
- Disable reason column: Explains why Outlook disabled the add-in, such as exceeding the load time threshold.
What the Slow and Disabled Add-ins Report Shows
Outlook tracks how long each add-in takes to load every time the program starts or when you open a new window. If an add-in takes more than 500 milliseconds to load, Outlook marks it as slow and may disable it automatically. The Slow and Disabled Add-ins report displays this data in a table so you can review load times and decide which add-ins to keep.
The report contains three columns:
- Add-in: The name of the add-in as registered in Outlook.
- Load Time (seconds): The total time the add-in took to load in the most recent session.
- Disable Reason: The reason Outlook disabled the add-in, such as “SLOW” or “CRASH”.
Add-ins that appear in the report with a load time above 0.5 seconds are candidates for removal or replacement. Outlook only disables add-ins that exceed 1 second consistently. The report updates after each Outlook restart.
How to Open the Slow and Disabled Add-ins Report
- Open the File menu
Click File in the top-left corner of the Outlook window. - Select Options
Click Options at the bottom of the left navigation pane. The Outlook Options dialog opens. - Go to the Add-ins tab
In the left pane, click Add-ins. The right pane shows a list of active, inactive, and disabled add-ins. - Locate the Slow and Disabled section
Scroll down to the Slow and Disabled Add-ins section at the bottom of the page. Click the View Slow and Disabled Add-ins link. A separate dialog opens with the report table. - Read the data
Review the Load Time and Disable Reason columns. Add-ins with load times above 0.5 seconds may cause performance issues. Add-ins with a Disable Reason of “SLOW” were automatically disabled by Outlook.
The report does not include add-ins that loaded within the acceptable threshold. If no add-ins appear in the report, all add-ins loaded within the 500-millisecond limit.
How to Interpret Load Time Values
Load times in the report are measured in seconds. A value of 0.3 means the add-in took 300 milliseconds to load. A value of 2.5 means it took 2.5 seconds. Outlook considers any add-in with a load time above 0.5 seconds as slow. Add-ins with load times above 1.0 seconds are candidates for automatic disable.
The load time reflects the startup phase only. It does not measure how long the add-in takes to respond during normal use. An add-in that loads quickly may still cause delays when performing specific actions. The report does not capture those delays.
What to Do About Slow Add-Ins
- Disable the add-in temporarily
In the same Outlook Options > Add-ins dialog, select COM Add-ins from the Manage dropdown and click Go. Uncheck the add-in you want to disable. Click OK and restart Outlook. - Remove the add-in permanently
Uninstall the add-in from the Windows Control Panel or from the Settings app under Apps > Installed apps. Restart Outlook after removal. - Update the add-in
Visit the add-in publisher’s website to check for a newer version that may load faster. Install the update and restart Outlook. - Contact the add-in vendor
If the add-in is essential and no update exists, contact the vendor with the load time data from the report. The vendor may provide a configuration change or a fix.
If an Add-In Is Disabled Without a Clear Reason
Sometimes Outlook disables an add-in even if it did not load slowly. The Disable Reason column may show “CRASH” if the add-in caused Outlook to close unexpectedly. It may show “HANG” if the add-in stopped responding. In both cases, the add-in is unreliable and should be removed.
If the Disable Reason column is blank, the add-in was disabled manually by the user or by an administrator through Group Policy. The report does not show the reason for manual disable.
Common Add-In Performance Issues and Fixes
Outlook Starts Slowly Even After Disabling All Slow Add-Ins
If Outlook remains slow after disabling the add-ins listed in the report, check the COM Add-ins list for add-ins that did not appear in the report. Some add-ins may load within the threshold but still consume resources during initialization. Disable add-ins one by one and restart Outlook after each change to identify the problem.
An Add-In That Was Disabled Automatically Reappears as Enabled
Outlook re-enables a disabled add-in if the load time drops below the threshold in a later session. This can happen if the add-in’s load time varies. To prevent re-enable, remove the add-in permanently through the Control Panel or Settings app. Alternatively, configure Group Policy to disable the add-in centrally.
The Slow and Disabled Add-Ins Report Is Empty
An empty report does not guarantee that all add-ins are fast. It only indicates that no add-in exceeded the load time threshold during the last session. Some add-ins may cause delays after loading, such as when they query a server or update a pane. Use the COM Add-ins list to disable add-ins manually and test performance.
| Item | Slow and Disabled Report | COM Add-ins List |
|---|---|---|
| Purpose | Shows add-ins that exceeded the load time threshold or caused crashes | Shows all installed COM add-ins regardless of performance |
| Data provided | Add-in name, load time in seconds, disable reason | Add-in name, status (active/inactive/disabled), location path |
| Action allowed | Read-only view — no enable or disable option | Enable or disable add-ins by checking or unchecking the box |
| Updates | Refreshes after each Outlook restart | Reflects changes immediately after clicking OK |
The Slow and Disabled Add-ins report gives you a quick view of add-in load performance. Use the COM Add-ins list to take action on slow or problematic add-ins.
You can now open the Slow and Disabled Add-ins report and interpret the load time values. Use the data to decide which add-ins to disable or remove. For persistent performance issues, disable all third-party add-ins first, then re-enable them one by one while testing Outlook startup speed. If you use Exchange Online, check the Microsoft 365 admin center for add-in performance reports that cover all users in your organization.