Hi Tony,
I don't have any direct experience with files that large. What version of Excel are you using? 2010 has 16,000+.
Are all 40 projects running for the next 3 months? Can you create a consolidated project with just the active ones?
If a remember, you are quite the programmer. See if
https://msdn.microsoft.com/en-us/lib...ffice.12).aspx
helps get you started.