I have recently run into a problem where I need to switch to manual calc in
order to speed up the work I was doing. However, the act of switching from
automatic calc to manual calc both by-hand and within VBA causes my project
to stall for a good minute or two before continuing with whatever it was
doing. For comparison, doing a full calculation of my workbook would normally
take about 4 seconds.

I am simply executing this line of code:
Application.Calculation = xlManual


My question is what exactly is happening when I "switch" from auto to manual
calculation that may be causing this stall?

Pertinent information:
- I currently have references from this workbook to 62 other workbooks.
- Many of these references are array formulas (but remember that a normal
full calculation would only take about 4 seconds)