Sheet size and memory usage in excel - vba

Question

Each worksheet is getting to large memory wise, I found that if I copied the rows and columns that had data in them and put into a new sheet then deleted the old one and renamed the new one the same name I could shrink my workbook size by 1 to 3 megabytes, its not a memory problem exactly but my code seems to run quicker when the book is smaller. I downloaded a program that is sopposed to delete all unused cells but cannot get it to work.
Sub Reset_LastCell()
' http://support.microsoft.com/default...&Product=xlw2K
' Save the lastcell and start there.
Dim Sh As Worksheet
Dim A As Integer
For Each Sh In Worksheets
A = A + 1
If A >= 28 Then
Sh.Activate
Set lastcell = Cells.SpecialCells(xlLastCell)
' Set the rowstep and column steps so that it can move toward
' cell A1.
rowstep = -1
colstep = -1
' Loop while it can still move.
While (rowstep + colstep <> 0) And (lastcell.Address <> "$A$1")
' Test to see if the current column has any data in any
' cells.
If Application _
.CountA(Range(Cells(1, lastcell.Column), lastcell)) _
> 0 Then colstep = 0 'If data then stop the stepping
' Test to see if the current row has any data in any cells.
' If data exists, stop row stepping.
If Application _
.CountA(Range(Cells(lastcell.Row, 1), lastcell)) _
> 0 Then rowstep = 0
' Move the lastcell pointer to a new location.
Set lastcell = lastcell.Offset(rowstep, colstep)
' Update the status bar with the new "actual" last cell
' location.
Application.StatusBar = "Lastcell: " & lastcell.Address
Wend
' Clear and delete the "unused" columns.
With Range(Cells(1, lastcell.Column + 1), "IV65536")
Application.StatusBar = "Deleting column range: " & _
.Address
.Clear
.Delete
End With
' Clear and delete the "unused" rows.
With Rows(lastcell.Row + 1 & ":65536")
Application.StatusBar = "Deleting Row Range: " & _
.Address
.Clear
.Delete
End With
' Select cell A1.
' Reset the status bar to the Microsoft Excel default.
Application.StatusBar = False
If A >= 35 Then Exit Sub
Range("AI2").Select
End If
Next
End Sub

Answer 1

One very easy means of reducing the workbook size is to save the file as a .xlsb. All code and all functions continue to work exactely the same. The only limitation is that the workbook can no longer be opened by Libre Office and other open source spreadsheet applications.
I have found that it also helps to speed up calculations of formulas... it may help with code.
UPDATE
Your code works fine on my machine, the only thing I needed to do was add Dim to the code because i use Option Explicit. Add the following to your code at the top:
Dim lastcell As Range
Dim colstep As Long
Dim rowstep As Long