I am calling an Excel session from another application.
When run from the GUI (and Excel has focus), the Workbook
takes about 0.2 seconds to recalculate. When called from
my VB application however, recalculation takes around 25
seconds. When run from the Excel GUI and Excel does not
have focus, recalculation also takes 25 seconds.

I've seen other messages that describe the same problem
and associate the slow down with the difference between a
foreground and background Windows process. This does not
seem to be the complete problem because even if I
increase the priority of the Excel process, I cannot
significantly improve performance.

Any recommendations on how to improve recalculation
performance of background Excel sessions?