Binaryworld - Simple variables are always faster than array elements ... [ VB -> Arrays ]

Reading and writing an item of an array is always slower than accessing a simple variable. Therefore, if you need to repeatedly use the same array item in a loop, you should assign it to a temporary variable and use that variable instead. I've included an example of this technique that scans an Integer arrays to see if there are any duplicate values:

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Function AnyDuplicates(intArray() As Integer) As Boolean
  ' returns True if the array holds duplicate values
  Dim i As Long, j As Long,
  Dim lastItem As Long
  Dim value As Integer

  ' evaluate UBound() just once
  lastItem = UBound(intArray)
  For i = LBound(intArray) To lastItem
    ' storing intArray(i) into a non-array variable
    ' saves an indexing operation within the inner loop
    value = intArray(i)
    For j = i + 1 To lastItem
      If value = intArray(j) Then
        AnyDuplicates = True
        Exit Function
      End If
    Next
  Next
  ' no duplicates were found
  AnyDuplicates = False
End Function

The routine is based upon two nested loops and saves CPU time by caching the value of intArray(i) into a regular, non-array variable. This simple trick makes the routine up to 80 percent faster.