I have a longish do-while loop in a VBA fnc. (code, below) If only
this workbook is open, it completes in < 1 sec. If any other workbook
is open, execution time increases to many seconds.

My guess is that the 'application.calculate' is giving up the baton to
any other workbook, and the task switching is causing the slowdown. Is
this plausible?

Bottom line: ss there a way to speed this up? Any ideas would be
appreciated.

Thanks,
George

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Loop code:

Do
N = 200
Do
N = N - 1

Range("wt_use").Value = Range("wt_new").Value

Range("control").Value = _
Range("control").Value + Range("adj").Value

Application.Calculate
Loop While ((Abs(Range("min_err").Value) 0.01) _
And (N 0))
M = M + 1
Loop While ((Range("max_chg").Value 0.01))