speed up the processing of excel vba - vba

Question

I've created excel vba file. However, it takes very long time to run the whole file because the total of the rows is up to 270,000 lines. Does anyone know how can I speed up the running process? Any help would be much appreciated. Thanks in advance.
Sub datemodifiedFile()
Dim File1 As Object
Dim fso As Object
Set fso = CreateObject("Scripting.FileSystemObject")
Set File1 = fso.getfile("C:\Users\Meg\Desktop\Master File.xlsx")
If Sheets("today").Range("B1").Value = File1.DateLastModified Then
Else
Sheets("today").Range("B1").Value = File1.DateLastModified
Dim WbB As Workbook
Set WbB = Workbooks.Open(Filename:="C:\Users\Meg\Desktop\Master File.xlsx", ReadOnly:=True)
Dim SheetB As Worksheet
Dim lastrow As Long
Set SheetB = WbB.Sheets("Sheet1")
SheetB.Select
Rows("1:1").Select
'Selection.AutoFilter
'ActiveSheet.Range("A:V").AutoFilter Field:=20, Criteria1:=""
Columns("A:V").Select
Selection.Copy
ThisWorkbook.Activate
Sheets("today").Select
Range("C1").Select
Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
:=False, Transpose:=False
'Columns("A:X").Select
'ActiveSheet.Range("$A$1:$X$750001").RemoveDuplicates Columns:=Array(3, 4, 6), _
Header:=xlYes
Application.CutCopyMode = False
lastrow = Sheets("today").Range("D" & Rows.Count).End(xlUp).Row
Sheets("today").Cells(lastrow, 3).EntireRow.Delete
WbB.Close False
End If
End Sub
Sub dltnew()
Dim i As Long
Dim lrow As Long
lrow = Sheets("today").Range("C" & Rows.Count).End(xlUp).Row
For i = 2 To lrow
If Sheets("today").Cells(i, 2).Value = "NEW" Then
Sheets("today").Cells(i, 2).Value = ""
Sheets("today").Cells(i, 1).Value = ""
End If
Next i
End Sub
Sub comdate()
Dim Sheet1 As Worksheet
Dim Sheet3 As Worksheet
Dim lrow As Long
Dim i As Long
Set Sheet1 = ThisWorkbook.Sheets("main")
Set Sheet3 = ThisWorkbook.Sheets("today")
Sheet3.Range("A1").Value = Date
Sheet3.Range("A1").NumberFormat = "dd/mm/yyyy"
Sheet3.Range("A1").Font.Color = Sheet3.Range("A1").Interior.Color
Sheet3.Columns("A:A").EntireColumn.Hidden = False
If Sheet1.Range("B1").Value <> Sheet3.Range("A1").Value Then
Sheet1.Range("B1").Value = Sheet3.Range("A1").Value
lrow = Sheet1.Range("C" & Rows.Count).End(xlUp).Row
For i = 2 To lrow
If Sheet1.Cells(i, 2).Value = "NEW" Then
Sheet1.Cells(i, 2).Value = ""
End If
Next i
End If
End Sub
Sub Con()
Dim LasRow As Long
Application.ScreenUpdating = False
LasRow = Sheets("today").Range("C" & Rows.Count).End(xlUp).Row
Sheets("today").Range("A2:A" & LasRow).Formula = "=C2&G2&I2"
ActiveSheet.AutoFilterMode = False
Application.ScreenUpdating = True
End Sub
Sub Compare()
Dim mrow As Range, trow As Long
With Worksheets("main")
Set mrow = .Range("A2", .Range("A" & Rows.Count).End(xlUp))
End With
trow = Worksheets("today").Range("A" & Rows.Count).End(xlUp).Row
With Worksheets("today")
For j = 2 To trow
If mrow.Find(What:=.Range("A" & j).Value, LookIn:=xlValues, LookAt:=xlWhole) Is Nothing _
Then .Range("B" & j).Value = "NEW"
Next j
End With
End Sub
Sub getnew()
Dim Sheet1 As Worksheet
Dim Sheet3 As Worksheet
Dim lastrow As Long
Dim i As Long
Dim erow As Long
Set Sheet1 = ThisWorkbook.Sheets("main")
Set Sheet3 = ThisWorkbook.Sheets("today")
lastrow = Sheet3.Range("C" & Rows.Count).End(xlUp).Row
For i = 2 To lastrow
If Sheet3.Cells(i, 2).Value = "NEW" Then
erow = Sheet1.Range("C" & Rows.Count).End(xlUp).Row + 1
Sheet3.Cells(i, 2).EntireRow.Copy Destination:=Sheet1.Range("A" & erow)
Application.CutCopyMode = False
Sheet1.Select
Range("A1:X750001").Select
Selection.Sort Key1:=Range("G2"), Order1:=xlAscending, Key2:=Range("C2") _
, Order2:=xlAscending, Header:=xlGuess, OrderCustom:=1, MatchCase:= _
False, Orientation:=xlTopToBottom
End If
Next i
End Sub
Sub hidecellvalue()
Dim Sheet1 As Worksheet
Dim lastrow As Long
Dim k As Long
Set Sheet1 = ThisWorkbook.Sheets("main")
lastrow = Sheet1.Range("B" & Rows.Count).End(xlUp).Row
For k = 2 To lastrow
If Sheet1.Cells(k, 1).Value <> "NEW" Then
Sheet1.Cells(k, 1).Font.Color = Sheet1.Cells(k, 1).Interior.Color
'Sheet1.Columns("A:A").EntireColumn.Hidden = False
End If
Next k
End Sub
Sub hideSh1column()
Dim Sheet1 As Worksheet
Set Sheet1 = ThisWorkbook.Sheets("main")
Sheet1.Columns("A:A").EntireColumn.Hidden = True
Sheet1.Columns("D:F").EntireColumn.Hidden = True
Sheet1.Columns("H:H").EntireColumn.Hidden = True
Sheet1.Columns("L:L").EntireColumn.Hidden = True
Sheet1.Columns("N:N").EntireColumn.Hidden = True
Sheet1.Columns("P:P").EntireColumn.Hidden = True
End Sub
Sub HideSheet3()
Sheets("today").Visible = xlSheetVisible
End Sub

Answer 1

I would start with remove as much as .activate and select you have in your code and replace it with proper sheet.cell/range selection.
Then i would add this on beggining of your code
Dim previousScreenUpdating As Boolean
previousScreenUpdating = Application.ScreenUpdating
Application.ScreenUpdating = False
Dim previousCalculation As XlCalculation
previousCalculation = Application.Calculation
Application.Calculation = xlCalculationManual
and this on the end of your code
Application.ScreenUpdating = previousScreenUpdating
Application.Calculation = previousCalculation

Answer 2

This should be much faster.
You should always try to do as much using arrays as possible, rather than going through your data cell-by-cell.
In addition, a dictionary-based lookup is always going to beat using Find() when you're checking things in a large loop.
Sub Compare()
Dim mrow As Range, trow As Long, arr, r As Long
Dim d As Object, rngV As Range
Dim arrV, arrN, wsT As Worksheet, wsM As Worksheet
Set d = CreateObject("Scripting.Dictionary")
Set wsM = Worksheets("Main")
Set wsT = Worksheets("today")
'get all unique values in ColA on Main
arr = wsM.Range(wsM.Range("A2"), wsM.Cells(wsM.Rows.Count, 1).End(xlUp)).Value
For r = 1 To UBound(arr, 1)
d(arr(r, 1)) = 1
Next r
Set rngV = wsT.Range(wsT.Range("A2"), wsT.Cells(wsT.Rows.Count, 1).End(xlUp))
arrV = rngV.Value 'values from colA as array
arrN = rngV.Offset(0, 1).Value 'values from colB as array
'check colA against the dictionary and update colB array as needed
For r = 1 To UBound(arrV, 1)
If Not d.exists(arrV(r, 1)) Then arrN(r, 1) = "NEW"
Next r
'repopulate ColB with updated data
rngV.Offset(0, 1).Value = arrN
End Sub