Is the formula slowing the worksheet down? I ask because this is simple arithmetical formula which needs not much resources.

When yes, then of-course you can write a VBA procedure, which counts the number of rows in UsedRange, and processes then every datarow in your table, calcualtes same formula in VBA (you have to remember, that in VBA FALSE is 0 like in worksheet, but TRUE converts to -1, so you hafe to multiply the result with -1) for every row, and writes the result into proper column in your table. You can run the procedure from button on worksheet, or you can create a shortcut key combination to run it.

I myself don't have Office available for today and tomorrow.