Latency, slippage, and why microseconds matter

To anyone outside trading, the industry’s obsession with microseconds looks absurd. Why spend fortunes on co-location, kernel-bypass networking, and NUMA-pinned cores to shave time no human could perceive? The answer is that in electronic markets latency is not a bragging right — it is a direct, measurable input to how much a trade costs and whether it fills at all.

§01Where the microseconds go

Tick-to-trade is the round trip from a market-data packet arriving to an order leaving the box. Every layer adds time: the NIC, the kernel network stack, the decode of the market-data protocol, the strategy decision, the order encode, and the wire back to the matching engine. Serious systems measure each segment end to end, because you cannot improve what you do not instrument.

§02How latency becomes slippage

Slippage is the difference between the price you expected and the price you got. When your view of the book is even a few microseconds stale, the resting order you tried to hit may already be gone, and the price you print may be worse than the one that triggered your decision. The slower you are, the more often you arrive after the opportunity has already been taken by someone faster.

§03Adverse selection: the hidden tax

For a market maker, latency has a second, subtler cost: adverse selection. Your quotes are most likely to be hit precisely when they are wrong — when the market is moving against you and you were too slow to pull them. Fast cancel logic is not about greed; it is about not being the last quote standing when the price gaps. A maker who cannot update quotes quickly gets picked off systematically.

§04When speed stops mattering

Latency is not the whole game. For a slow, scheduled execution algorithm working a large order over hours, microseconds are almost irrelevant next to sizing and impact modelling. The discipline is knowing which regime you are in and spending engineering where it actually converts to P&L. The figures and scenarios here are illustrative and educational, not a promise of results.