Improve Loop, Copy Speed

I have a large worksheet (Sheet1) containing approximately 15,000 records (15,000 rows x 21 columns). I need to search through all these records, and manually decide whether a record should be copied onto another worksheet (Sheet2) or not. The code I have written works very well (as far as I can tell), but it is extremely slow (the searching takes forever).

The code is as follows:

Sub SearchAndCopy()
Dim SearchRow As Long
Dim LastRow As Long
Dim SearchColumn As Long
Dim LastColumn As Long
Dim CopyToRow As Long
Dim SearchString As String
Dim Found As Boolean
Dim Response As Integer
On Error Goto Err_Execute
Found = False
'Fetch Search Term
Sheets("Sheet2").Select
SearchString = LCase( Range("F3").Text)......................