Do formulas update when copying data?

[Red Kenny]

I'm having a slight issue.

I've created a colossal sized data table that pulls through from multiple files via sumproduct. As is it well over 100k lines long with sumproducts on multiple columns * 100k rows, it takes a while to process.

That said, when I go to copy 2 columns of data when I CTRL + C it seems to re-calc the entire workbook (bear in mind I always keep manual calculation on). If this is the case, any way to prevent this?

Thank you.

 

[Derek Brown]

Assuming that you are not running any VBA code that changes the calculation mode, I wonder if you are opening this workbook while already having another open - and that has calculation mode set to automatic?
Have a look at the following that describes how the first workbook opened determines the calculation mode for any others opened in the same instance of Excel:
https://support.microsoft.com/en-us/help/214395/how-excel-determines-the-current-mode-of-calculation