Terry Pinnell wrote:

Anyone else seeing the subject behaviour please? More important, how
to fix it? It's such a disappointing aspect compared to my old Excel
2000 with Win XP.

On d-clicking an .xlsm file in Windows 10 File Explorer, Excel itself
loads quickly, but it then takes around 5 seconds or so for the
workbook to open.

Pleased to report I've found the cause. Following up a suggestion from
the guys in the alt.comp.os.windows-10 newsgroup, I investigated
add-ins. Turns out there are three types and this was a 'COM Add-in'.

https://dl.dropboxusercontent.com/u/...Ins-3types.jpg
https://dl.dropboxusercontent.com/u/...elAddIns-2.jpg

I have no idea why it got installed in Excel. Maybe a default option I
missed when I
re-installed my Space Navigator to use with Google Earth.
http://www.3dconnexion.co.uk/product...navigator.html


But with that now unchecked, my worksheets open in a flash ;-)

--
Terry, East Grinstead, UK