Find Value In Column & Delete All Rows Below

I have searched high and low for a more efficient macro than the current loop i have. I have a range that varies in size but always follows the same format. After i reach a certain value output from a formula, "4", I want to delete all lines below that line. So I want to find value "4" then move one row down and delete all lines to line 2004. I have attached the macro that i compiled but it takes a couple of minutes to run.

Sub manual()
Dim Firstrow As Long
Dim Lastrow As Long
Dim Lrow As Long
Dim CalcMode As Long
Dim ViewMode As Long
With Application
CalcMode = .Calculation
.Calculation = xlCalculationManual
. ScreenUpdating = False
End With
With ActiveSheet
.Select
ViewMode = ActiveWindow.View
ActiveWindow.View = xlNormalView.................