Question

what is the point of doing these:

Application.ScreenUpdating = False
Application.DisplayAlerts = False

does it really save that much time?

Answer 1

Agree.

I have found that when you turn off ScreenUpdating, Calculation, it’s best to think about how to do as much work (writes,reads,events,…) as possible for as few ScreenUpdating calls in return. This will speed up operations while also providing the user with a better and more tolerable experience. Say, for example that you want to write some data to a sheet as fast as possible. You could do this:

For Each row In rowDic.Keys()
    ' turn off updating
    for item in rowDic.Key(row)
        ... do some writes
    Next             
    ' turn on updating
Next

or to go faster you could do this:

' turn off updating
For Each row In rowDic.Keys()
    for item in rowDic.Key(row)
        ... do some writes
    Next             
Next
' turn on updating

Similarly, when writing data, it’s quickest to write larger chunks, fewer times. so the ideal number of writes, if any, is one. You can do this by treating a Rangeas a 2D array[rows,cols]. I have found the following to be effective:

' turn off updates

' Organise data in ram so that it fits the range for which it is meant
Dim two_d_arr (rows,cols)
loadDataFromSource two_d_arr

Dim destinationRange as Range
destinationRange = Sheets(someSheet).Range(someRange).Value = two_d_arr

Redim two_d_arr(0,0) ' !!! RELEASE MEMORY
' turn on updates

Here, there are no loops, this optimises each individual task’s time in the CPU which results in quicker processing times and in turn seems to make excel work normally (not crash).

HTH,

F