Welcome to the Board!
Your question is a bit confusing.
I am guessing you mean "MS Excel" and not "Mos Excel". I believe that "MOS Excel Specialist" is a professional designation, not a program (not sure why you are mentioning it here).
When you say "40%", what exactly are you referring to? Is is the Calculation percentage?
If so, do you have a ton of calculated fields on your file? If so, how many calculations are we talking about (how many cells have formulas in them)?