How to Profile Word’s Add-in Load Time to Find the Slow One

Word takes too long to start, and you suspect one of your add-ins is to blame. Every time Word loads, it initializes all enabled add-ins, and a poorly written or outdated add-in can add seconds or even minutes to the startup process. This article explains how to measure each add-in’s load time using Word’s built-in performance profiler. You will learn to identify the slow add-in and decide whether to disable it permanently.

Why Add-ins Slow Down Word Startup

Word add-ins are external programs that extend the application’s functionality. They can be COM add-ins, VBA macros, or Office Web Add-ins. When Word starts, it loads every enabled add-in into memory. Each add-in runs its own initialization code, which may include connecting to a network service, reading configuration files, or loading large data sets. A single slow add-in can delay the entire startup process because Word waits for each add-in to finish loading before showing the user interface.

The root cause of slow add-ins is usually inefficient code, outdated libraries, or reliance on external resources that are slow to respond. For example, an add-in that tries to contact a server on the internet will hang if the server is unreachable. Word does not have a built-in timeout for add-in initialization, so a stuck add-in can cause an indefinite delay.

Types of Add-ins That Cause Delays

COM add-ins are the most common source of startup delays because they run native code and have full access to the Windows operating system. VBA add-ins, such as global templates with Auto macros, can also slow down startup if they contain complex initialization routines. Office Web Add-ins run in a sandboxed browser environment and typically have less impact, but they can still cause delays if they load large JavaScript files or make network calls.

Steps to Profile Add-in Load Time Using the Registry and Event Viewer

Word does not show add-in load times in the user interface. You must enable a hidden performance logging feature through the Windows Registry and then read the results from Event Viewer. The following steps work for Word 2016, Word 2019, Word 2021, and Word for Microsoft 365 on Windows 10 and Windows 11.

1. Close Word completely
   Make sure no Word process is running in the background. Open Task Manager with Ctrl+Shift+Escape and end any Word tasks you find.
2. Open Registry Editor
   Press Windows+R, type regedit, and press Enter. Click Yes if prompted by User Account Control.
3. Navigate to the Word Performance key
   Go to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Performance. If the Performance key does not exist, right-click the Word folder, select New > Key, and name it Performance.
4. Create the EnablePerformanceLogging DWORD
   Right-click the Performance key, select New > DWORD (32-bit) Value, and name it EnablePerformanceLogging. Double-click the new value, set the data to 1, and click OK.
5. Start Word and let it load fully
   Open Word normally. Wait until the startup completes and the blank document or start screen appears. Then close Word.
6. Open Event Viewer
   Press Windows+R, type eventvwr.msc, and press Enter.
7. Locate the add-in load events
   In the left pane, expand Windows Logs and select Application. In the Actions pane on the right, click Filter Current Log. In the Filter dialog, type 1000 in the Event IDs field and click OK. You will see a list of events with Source = Word.
8. Read the load time for each add-in
   Double-click an event to open its details. In the Description field, look for lines like:
   Add-in: MyAddin.dll, Load time: 4500 ms
   The number after Load time: is the time in milliseconds that the add-in took to initialize. Repeat this for each event to find the slowest add-in.
9. Disable the slow add-in
   Go to File > Options > Add-ins. At the bottom of the dialog, set Manage to COM Add-ins and click Go. Uncheck the slow add-in and click OK. Restart Word to confirm the startup time improves.

Common Issues After Profiling Add-in Load Times

No Add-in Load Events Appear in Event Viewer

If you do not see any Event ID 1000 entries after enabling performance logging, the registry value may not have been applied correctly. Verify that the EnablePerformanceLogging DWORD is set to 1 under the HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Performance key. Also confirm that you closed Word before editing the registry. If the key path is incorrect, logging will not activate.

Word Still Starts Slowly After Disabling the Slow Add-in

If disabling one add-in does not fix the startup delay, another add-in may also be slow. Run the profiling steps again to identify the next slowest add-in. In some cases, multiple add-ins each add a small delay that adds up to a noticeable lag. Disable all non-essential add-ins and re-enable them one at a time to find the combination that causes the issue.

Add-in Load Time Is Very Short but Startup Is Still Slow

If the Event Viewer shows all add-ins loading in under 100 ms but Word still starts slowly, the problem is not the add-ins. Consider other causes such as a large Normal.dotm template, a corrupted Word Data key in the registry, or a slow hard drive. Try starting Word in Safe Mode by holding Ctrl while launching Word. If Safe Mode starts quickly, the issue is likely an add-in or customization that the profiler did not capture.

Registry Profiling vs Safe Mode Testing: Finding the Slow Add-in

Item	Registry Profiling	Safe Mode Testing
Method	Enables performance logging in Registry and reads Event Viewer	Starts Word with all add-ins disabled by holding Ctrl on launch
Time required	10 to 15 minutes for setup and analysis	30 seconds per test
Granularity	Shows exact load time for each add-in in milliseconds	Only tells you if any add-in is causing a problem, not which one
Best for	Isolating the specific slow add-in among many	Quickly confirming that add-ins are the root cause

Use registry profiling when you have many add-ins and need precise data to decide which to disable. Use Safe Mode testing for a fast check when you just want to know if add-ins are involved.

You can now measure each add-in’s load time using the Registry and Event Viewer, then disable the slowest one from the COM Add-ins dialog. After disabling the culprit, restart Word and verify the startup speed. For persistent issues, repeat the profiling to catch secondary slow add-ins, or use Word Safe Mode to rule out other customization problems. As an advanced tip, you can export the Performance registry key as a .reg file and deploy it to multiple machines using Group Policy to profile add-in performance across your organization.