Excel slow to start spreadsheets when started outside of excel

Excel 2021. If no spreadsheet running and I click on a shortcut to a spreadsheet, it starts right up. If I

1. click on another shortcut to a spreadsheet,

2. try to launch a CSV file from my browser I've just downloaded, or

3. start a csv file in cmd

they all take between 8 and 15 seconds to start. If the currently open spreadsheet does not have focus, it gets focus immediately but the "new" spreadsheet still takes some time. If I start a 2nd spreadsheet from the File->Open inside the current spreadsheet it starts right up.

I do have a personal.xls in XLStart that contains but a single macro. And XLStart is in my trusted locations.

ideas?

/steve