Why is it not faster?

[Gustav]

The Garmin Gekko (small and pretty cheap)i've got seems to work well,gives fairly consistant repeatable readings anyway,i don't normally keep it at max for long,a second or two maybe,but it gives the same reading if you keep it there for longer.As long as it covers a few metres at max speed it seems to be ok.But yeah,ideally radar would be better.