Good Morning rb7,
Can you please explain why you say this? Why is latency least of your concern if you do manual?
Sure.
If you do manual trading, you usually go like this:
1) You look at the chart or whatever data representation you use.
2) You think of what you will do based on your system/model.
3) Then you manually enter your order (on DOM or else) with you mouse or keyboard.
All those steps will take you what, 1, 2, 3 seconds (if your fast!!).
And I'm not even including the time is takes for you application to received and show the market data.
So, it's not a couple of hundred of milliseconds that will make a big difference in this case.
FWIW, IB round trip response time between the time a market order is sent and the time the fill is received is around 250 ms. If a faster broker exists (very probable), you will save what, 50,100, 200 ms. 100 ms substracted from 2-3 seconds will not make a big difference (percentage wise).
Manual trading is slow by definition.
But if someone is using a broker that takes many seconds to process and transmit the order to the exchange, then it's another game.