tips for optimizing vb code

[krtxmrtz]

I actually think that the contents of the loop should be something that has nothing to do with A=A or I=J - something that's got more meat to it.

You bet. This is it:

'Loop #1
    '*************************************************
    For i = 0 To uLim
        For n = 1 To 3
            k = k + 1
            Vector(k) = Gray(i)
            If (k - GpL) Mod dummy = 0 Then
                For m = 1 To nb2a
                    k = k + 1
                    Vector(k) = 0
                Next
            End If
        Next
    Next
    
    'Loop #2
    '*************************************************
    i = 0
    Do
        n = 1
        Do
            k = k + 1
            Vector(k) = Gray(i)
            If (k - GpL) Mod dummy = 0 Then
                m = 0
                Do While m < nb2a
                    k = k + 1
                    Vector(k) = 0
                    m = m + 1
                Loop
            End If
            n = n + 1
        Loop While n <= 3
        i = i + 1
    Loop While i <= uLim

I tested it for these values:
uLim = 58805
nb2a = 2
GpL = 726
dummy = 728
For loop #1 the time was 0.328 s. whereas loop #2 took 0.437 s.