Loop that takes a long time

Hi,

The below look has to go through 30,000 lines and takes ages. Is there a more efficent way to achive the same outcome. All it does is concatenates columns 6 & 7 together.

x = 2
Do While Cells(x, 1).Value <> ""
Cells(x, 8).Value = Cells(x, 6).Value & " " & Cells(x, 7).Value
x = x + 1
Loop