[Development Journal] The Physical Constraint of Latency. Why VPS Selection Affects Reproducibility of Logic

Regardless of how much the superiority of the logic has been validated, whether that superiority can be reproduced in actual operation depends on other physical constraints. This time I want to document the representative factor, “latency,” and the selection of VPS (virtual private server) that influences it. It is a mundane yet essential variable that, although unrelated to the internal structure of the entry logic, can greatly affect the success of real-world operation. Like the previously recorded spread, slippage, and anomaly detection, it is positioned as one of the external risk factors that exist outside the logic itself.

1. Latency, a variable outside the logic

Latency refers to the communication delay that occurs from when an order is placed until it is filled. After the EA issues an order instruction, there is always a certain time difference before it reaches the broker’s server and is processed and filled. This time difference is a very small delay measured in milliseconds, but in rapidly changing markets, prices can move considerably within that brief time.

This delay is a purely physical/network constraint that occurs independently of the quality of the logic design. No matter how sophisticated the entry logic is, this delay cannot be zero, and in that sense latency is an unavoidable source of noise in all EA operations. Unless this variable is explicitly addressed during the validation phase, it is impossible to accurately estimate reproducibility in actual operation.

2. The structure of latency caused by the physical distance of VPS

The primary factor determining the magnitude of latency is the physical distance between the VPS location and the broker’s server. Data travels at speeds close to the speed of light, but as geographical distance increases, the number of network devices it passes through increases, and transmission delay accumulates.

Many brokers have servers in financial hubs such as London, New York, and Tokyo. Placing the VPS in the same or nearby data center as these servers can physically minimize latency. Conversely, placing the VPS far from these locations means that, even with high-spec environments, you cannot eliminate this physical delay factor. Software optimizations have limits, and, in the end, this issue reduces to hardware and network routing problems.

3. The gap between latency and validation vs. real operation

In environments with high latency, the market can move between order placement and execution, causing slippage at levels different from the expected price. This directly ties into the issues of spread and slippage previously noted.

In backtesting environments, this delay factor is not typically incorporated or is handled by simplified models, which creates a non-negligible gap between expected values in validation and actual performance in operation. Even if the logic itself has no defects, latency as an environmental factor can prevent the superiority from being reproduced in real operation. If this gap is mistaken for a “logic problem,” one might overlook infrastructure issues that should be addressed and waste time making changes to the logic itself.

4. Differences in resilience by logic type

The impact of latency varies greatly depending on the trading style of the logic. Scalping-type logic, where the per-trade profit margin is small, is highly sensitive to latency because even small delays disproportionately affect the expected value, resulting in very low resilience to latency.

Meanwhile, swing-type logic that captures longer-term trends tends to have larger per-trade profits, so the relative impact of the same latency is smaller. In other words, the priority for VPS selection costs changes depending on the design philosophy of the logic. When productizing scalping-type logic, latency validation should be treated on par with entry logic validation; a validation report that ignores this may fail to guarantee reproducibility in actual operation.

5. Technical checkpoints for VPS selection

In VPS selection, in addition to the physical distance to the broker server, the following factors must be checked. Prioritizing distance while neglecting specs and stability may lead to performance degradation due to other factors.

• Whether CPU and memory specs match the number of EAs running and the processing load
• Whether uptime (SLA) is high and stable operation is guaranteed
• Whether there is a robust support system in case of failures

Insufficient specs can create processing delays at a different layer, generating new latency, so choosing based solely on price can lead to unexpected performance degradation.

Why Semura Lab. includes latency as a validation item

At Semura Lab., in addition to validating the superiority of the logic itself, we treat environmental factors such as latency as indispensable variables in terms of how reproducible the logic is in real operation. No matter how excellent the backtest figures are, if the physical conditions of real operation are not in place, those figures cannot be reproduced. Our consistent stance is that logic validation and the validation of the environment that runs it should not be considered separately. In this development log, we will continue to honestly record such environmental factors.

? Any questions about markets or logic can be addressed at the Semura_Lab Yorozu Consultation Desk as well.
https://www.gogojungle.co.jp/mypage/community/485