Hi EnolaLv,
If your Office applications suddenly became slow and lag at the same time, it’s possible that conflicts have occurred. This could be due to an update that may have been installed on your PC. Just to confirm, which version of Office do you have on your computer? Have you noticed any updates or changes that were made prior to the issue?
For me to isolate this concern, I’d suggest that you open the Excel app or any of the Office applications in safe mode. This will disable any add-ins installed that may be causing the app to experience lagging issue. Here are the steps that you may follow:
- Find the shortcut icon of Excel or any of your Office apps.
- Press and hold the CTRL key, and click the application shortcut.
- Click Yes when a window appears asking if you want to start the application in safe mode.
Note: To stop Office Safe Mode, exit and restart your Office application. It will start in normal mode unless there's a problem opening the application.
If the issue doesn't persists while on safe mode, you can use the instructions below to identify which add-in is causing it to happen:
- Click File > Option > Add-ins, then click Go in the Manage: COM Add-ins.
- Clear the checkbox if you'll see any add-ins, then disable them.
- Close Excel or any of your Office apps and relaunch it after.
- Check if you'll still get the same behavior.
In case that there are no updates that have installed yet, I’d recommend that you check for any updates available and install it. Then, see if the Office app will no longer lag or become slow.
You may also run a repair. This is usually being used if an Office app isn’t working properly as it should be. Here’s an article that you can use to perform this action.
Let me know the result after trying the suggested steps.