Slow load of Excel file

If I click the Excel icon on my desktop, Excel opens in about two seconds.
Then I can open an Excel file in another two seconds. But if I go to my
computer or to Windows Explorer and click on the Excel file, it takes about
30 seconds for the file to load and open. This is a recent phenomenon. Can
somebody suggest how to restore the computer to a better level of performance?

Thanks,
--
JerryI