Excel file crashes and closes when I run the code, but results of the code who when I reopen the file - excel

Question

I am copying data under columns with matching headers between the source sheet and the destination sheet. Both the sheets are in the same excel file but they need to have a clarification number.
For example, one of the columns in the destination sheet has the the clarification number QM6754 and the row of data of QM6754. The source sheet also has the clarification number column but I dont want to copy it, I want to copy the other data in the row of this specific clarification number to the destination sheet that in one of its columns. this way the data isn't copied randomly and the entire row from each sheet relate to each other.
The code I used shows results(I modified it) but when I run it, the excel file shows (not responding) for about 3-4 minutes and then shutsdown or leaves a blank Excel sheet and VBA window. I close the excel file and reopen it and the data has been copied. The file is quite large and I have three pushbuttons that run this code for each sheet I want to copy data from. Three sheets with average of 3k-6k rows. But I cannot eliminate the rows.
The code runs but I would like to optimize of the way it runs because it isn't practical to run, close file and then open file again. Could the issue be with the For loop?
Sub CopyColumnData()
Dim wb As Workbook
Dim myworksheet As Variant
Dim workbookname As String
' DECLARE VARIABLES
Dim i As Integer ' Counter
Dim j As Integer ' Counter
Dim colsSrc As Integer ' PR Report: Source worksheet columns
Dim colsDest As Integer ' Open PR Data: Destination worksheet columns
Dim rowsSrc As Long ' Source worksheet rows
Dim WsSrc As Worksheet ' Source worksheet
Dim WsDest As Worksheet ' Destination worksheet
Dim ws1PRRow As Long, ws1EndRow As Long, ws2PRRow As Long, ws2EndRow As Long
Dim searchKey As String, foundKey As String
workbookname = ActiveWorkbook.Name
Set wb = ThisWorkbook
myworksheet = "Sheet 1 copied Data"
wb.Worksheets(myworksheet).Activate
' SET VARIABLES
' Source worksheet: Previous Report
Set WsSrc = wb.Worksheets(myworksheet)
Workbooks(workbookname).Sheets("Main Sheet").Activate
' Destination worksheet: Master Sheet
Set WsDest = Workbooks(workbookname).Sheets("Main Sheet")
'Adjust incase of change in column in both sheets
ws1ORNum = "K" 'Clarification Number
ws2ORNum = "K" 'Clarification Number
' Setting first and last row for the columns in both sheets
ws1PRRow = 3 'The row we want to start processing first
ws1EndRow = WsSrc.UsedRange.Rows(WsSrc.UsedRange.Rows.Count).Row
ws2PRRow = 3 'The row we want to start search first
ws2EndRow = WsDest.UsedRange.Rows(WsDest.UsedRange.Rows.Count).Row
For i = ws1PRRow To ws1EndRow ' first and last row
searchKey = WsSrc.Range(ws1ORNum & i)
'if we have a non blank search term then iterate through possible matches
If (searchKey <> "") Then
For j = ws2PRRow To ws2EndRow ' first and last row
foundKey = WsDest.Range(ws2ORNum & j)
' Copy result if there is a match between PR number and line in both sheets
If (searchKey = foundKey) Then
' Copying data where the rows match
WsDest.Range("AI" & j).Value = WsSrc.Range("A" & i).Value
WsDest.Range("AJ" & j).Value = WsSrc.Range("B" & i).Value
WsDest.Range("AK" & j).Value = WsSrc.Range("C" & i).Value
WsDest.Range("AL" & j).Value = WsSrc.Range("D" & i).Value
WsDest.Range("AM" & j).Value = WsSrc.Range("E" & i).Value
WsDest.Range("AN" & j).Value = WsSrc.Range("F" & i).Value
WsDest.Range("AO" & j).Value = WsSrc.Range("G" & i).Value
WsDest.Range("AP" & j).Value = WsSrc.Range("H" & i).Value
Exit For
End If
Next
End If
Next
'Close Initial PR Report file
wb.Save
wb.Close
'Pushbuttons are placed in Summary sheet
'position to Instruction worksheet
ActiveWorkbook.Worksheets("Summary").Select
ActiveWindow.ScrollColumn = 1
Range("A1").Select
ActiveWorkbook.Worksheets("Summary").Select
ActiveWindow.ScrollColumn = 1
Range("A1").Select
End Sub

Answer 1

To increase the speed and reliability, you will want to handle the copy/paste via array transfer instead of the Range.Copy method. Given your existing code, here's how a solution that should work for you:
Sub CopyColumnData()
'Source data info
Const sSrcSheet As String = "Sheet 1 copied Data"
Const sSrcClarCol As String = "K"
Const lSrcPRRow As Long = 3
'Destination data info
Const sDstSheet As String = "Main Sheet"
Const sDstClarCol As String = "K"
Const lDstPRRow As Long = 3
'Set variables based on source and destination
On Error Resume Next
Dim wbSrc As Workbook: Set wbSrc = ThisWorkbook
Dim wsSrc As Worksheet: Set wsSrc = wbSrc.Worksheets(sSrcSheet)
Dim wbDst As Workbook: Set wbDst = ActiveWorkbook
Dim wsDst As Worksheet: Set wsDst = wbDst.Worksheets(sDstSheet)
On Error GoTo 0
'Verify source and destination were found
If wsSrc Is Nothing Then
MsgBox "Worksheet """ & sSrcSheet & """ not found in " & wbSrc.Name
Exit Sub
End If
If wsDst Is Nothing Then
MsgBox "Worksheet """ & sDstSheet & """ not found in " & wbDst.Name
Exit Sub
End If
'Setup variables to handle Clarification Number matching and data transfer via array
Dim hDstClarNums As Object: Set hDstClarNums = CreateObject("Scripting.Dictionary") 'Clarification Number Matching
'Load Source data into array
Dim rSrcData As Range: Set rSrcData = wsSrc.Range(sSrcClarCol & lSrcPRRow, wsSrc.Cells(wsSrc.Rows.Count, sSrcClarCol).End(xlUp))
Dim aSrcClarNums() As Variant: aSrcClarNums = rSrcData.Value
Dim aSrcData() As Variant: aSrcData = Intersect(rSrcData.EntireRow, wsSrc.Columns("A:H")).Value 'Transfer data from columns A:H
'Prepare dest data array
Dim rDstData As Range: Set rDstData = wsDst.Range(sDstClarCol & lDstPRRow, wsDst.Cells(wsDst.Rows.Count, sDstClarCol).End(xlUp))
Dim aDstClarNums() As Variant: aDstClarNums = rDstData.Value
Dim aDstData() As Variant: aDstData = Intersect(rDstData.EntireRow, wsDst.Columns("AI:AP")).Value 'Destination will be into columns AI:AP
'Use dictionary to perform Clarification Number matching
Dim vClarNum As Variant
For Each vClarNum In aDstClarNums
If Not hDstClarNums.Exists(vClarNum) Then hDstClarNums.Add vClarNum, hDstClarNums.Count + 1
Next vClarNum
'Transfer data from source to destination using arrays
Dim i As Long, j As Long
For i = 1 To UBound(aSrcClarNums, 1)
For j = 1 To UBound(aSrcData, 2)
If hDstClarNums.Exists(aSrcClarNums(i, 1)) Then aDstData(hDstClarNums(aSrcClarNums(i, 1)), j) = aSrcData(i, j)
Next j
Next i
'Output to destination
Intersect(rDstData.EntireRow, wsDst.Columns("AI:AP")).Value = aDstData
'Save and close source workbook (uncomment next line if this is necessary)
'wbSrc.Close SaveChanges:=True
'Activate summary sheet, cell A1 in destination workbook (uncomment these lines if this is necessary)
'wbDst.Worksheets("Summary").Activate
'wbDst.Worksheets("Summary").Range("A1").Select
End Sub