遅いなら配列に入れるとか。

Sub Macro1()
 tmp = Range("G1:G" & Cells(Rows.Count, 7).End(xlUp).Row).Value
 For i = Cells(Rows.Count, 7).End(xlUp).Row To 2 Step -1
  If tmp(i, 1) = 1000 Then
   Rows(i).Delete
  End If
 Next
End Sub