How to prevent a macro from freezing / turning white the Excel window?

Question

So at work I am working on a macro/UserForm in Excel for someone. It works great (I think) and does exactly what it needs to do and takes under 1 minute to run, going through ~7

Answer 1

As @stuartd mentioned in the comments, DoEvents will probably allow the user to interact with Excel while the macro is running, and prevent Excel from becoming unresponsive.

An alternative approach is to speed up your code, so that it finishes before the user has reason to believe that it has crashed. In this vein, here are some suggestions:

1. Turn off Screen Updating: It is a lot of work for Excel to render the screen. You can free those resources to work on what you need done by adding Application.ScreenUpdating = False to the beginning of your code, and Application.ScreenUpdating = True to the end.

2. Turn off Calculations: If you have a lot of formulas running, this can slow down what happens when you place a value into the workbook, as it needs to recalculoate. My preferred way of dealing with this is to store the current calculation setting, turn off calculations, and then restore the original setting at the end.

Dim Calc_Setting as Long
Calc_Setting = Application.Calculation
Application.Calculation = xlCalculationManual
'Your code here
Application.Calculation = Calc_Setting

3. Use Worksheet Variables: You keep accessing your Worksheets by name. For repeated access, it should be faster to store that in a variable. Along with this, don't use Activate or Select. Fully reference you calls to Cells, so that it accesses the right worksheet.

Dim oldsheet as Worksheet, newsheet as Worksheet
Set oldsheet =  Worksheets(CStr(oldsheetname))
Set newsheet =  Worksheets(CStr(newsheetname))
oldsheet.Cells(place, x3) = ...

4. Use Variant Arrays: This should speed up your code the most, but also has a caveat. Excel and VBA are slow when they interact. Within your inner loop, VBA is accessing Excel 7 times. By pulling those interactions out of the loops, we can achieve a serious performance boost. The issue is that reading/writing arrays to Excel Ranges is still bound by the 2003 size limits (65536 rows, ...). If you expect to have more data than this, you will need to do some gymnastics to make it work.

Dim inVal as Variant, Output as Variant

inVal = Range(oldsheet.Cells(1,x1-2),oldsheet.Cells(x2+3-x1,y)).Value
redim output(1 to (x2-x1) * (y-x3) + 2, 1 to x3+2)
'These numbers are not tested, you should test.

'Loops to fill output.  This will need to be 1 entry at a time.

newsheet.Cells(x1,x1).Resize(Ubound(output,1), Ubound(output,2)).Value