A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
I have been battling with this problem too.
I wondered if the password length would make any difference to performance - I found not - but if you set a blank password
- then yes it is instant!
Protecting with a blank password locks the cells as usual with no performance problem.
Having a blank password has drawbacks - the user can unlock simply by clicking the Un-Protect sheet button.
However If users cannot save the sheet (a macro in on save event can prevents this) then this could help you - my problem is solved until a better workaround is suggested.
If interested in XL-Database integration - you can see our work here :