To increase speed, you must decrease computation and memory access. The less computation and memory access possible, the smaller the variety of strategies possi

To increase speed, you must decrease computation and memory access. The less computation and memory access possible, the smaller the variety of strategies possible. In regular timescales, the strategy space is much larger than the number of machines / agents competing. The ratio of the number of agents to the number of possible strategies approaches zero. As more machines compete in nanosecond time scales, the ratio of the number of machines to the number of strategies in this restricted space becomes much larger. As this ratio increases, the system dynamics undergo a phase shift. The probability of dramatic movements becomes much greater. When too many agents are crowded onto the same strategy, they all try to take the same side of a trade -- liquidity disappears. This was the cause of the flash crash of 2010, and will be the cause of many more.