A latency model gives the delays between the market and the strategy: the market-data latency, from an event at the exchange to the strategy seeing it, and the order-entry latency, from the strategy sending an order or cancellation to the exchange acting on it.
firm.tape under three queue-position models, against the order-entry latency (the market-data latency is half of it). Only the front-of-queue model, which no real order enjoys, makes money. Data: rs_lobreplay.touch_grid.