Quote from fickletrader:
I trade 5 second time frame, automated with Interactive Brokers. The biggest difference between 5 second and 1 second time frame in my experience is the effectiveness of market orders vs limit orders and the difficulty of simulating what happens at 1 second intervals due to latency and execution time. 1 second time frame doesn't have a huge advantage over 5 second time frame unless you've got accurate level 2 depth historical data and the capacity to reliably simulate limit orders.
Traders operating at sub 5 second time frame "make odds" on the order book, almost exclusively by posting and cancelling limit orders, thus taking on the role of liquidity provider. They reduce their transaction costs by arranging a "rebate" commission structure with their broker: the higher their volume, the smaller their commission bill is (it can even go negative, where the broker pays them). This is the modern equivalent to owning a seat on the exchange, which entitled the trader to operate on the floor without paying commission.
My conclusion is that since I don't want to play that low-margin, high overhead game, I may as well take my directional trades at 5 seconds using market orders instead of taking on the trading desks at <= 1 second but blind without the order book and at the whims of my VMWare host's ISP.