If your Excel program says not responding, keeps freezing up or lagging, there are several ways you might be able to resolve this issue.

It might even give the message:

"Microsoft Excel is not responding. If you restart or close the program, it will try to recover your information." Then it gives the option to either "Restart the program", Close the program", or "Wait for the program to respond".

If so, this video will walk you through each of these steps to troubleshoot the issue.

1. Open in Safe Mode. Now Disable Addins one by one to see if one of them is the culprit.
2. Run Office Repair.
3. Clear Conditional Formatting & Rules. (Save a new copy)
4. Delete Special Objects.