Excel - INSANELY SLOW load times with Win 8

At work we have a few computers that have Windows 8 (installed in Feb some time) that have recently started moving insanely slow when opening our main log spreadsheet in Excel. We have taken off all the infinite formatting such as shading and such but there seems to be checkboxes stacked on top of each other and we can't delete them unless we do it one at a time. I have tried selecting them as objects and I don't know if it is because there are too many of them, but they won't select either. And when I try to load the object list it stalls etc etc so I am wondering how they might have all duplicated themselves and how do I get rid of them?

I guess my question is would this make a difference and why if Windows 8 is an UPGRADE??

Is anyone else struggling with this?

Thanks in advance!

Vic

 

Also, there are not any real formulas or formatting and the workbook itself is only 12 pages of the exact same thing for each month of the year.

 

Sorry for all the replies but I am adding things as they occur as well, one of the users is having a problem with the file saving as .xlsb - binary file. What would cause this?

It is saying that it has found a problem with some content and then tries to change the file type.