6 must-know traits of zero latency System Design

Milliseconds matter.

• A stock trader loses thousands when an order executes a fraction of a second too late.

• A competitive gamer watches in frustration as lag causes them to miss the winning shot.

• An autonomous vehicle has only milliseconds to react to a pedestrian in its path – and any delay could be fatal.

In real-time systems, latency is more than an inconvenience—it’s the enemy.

But the challenge is that true "zero latency" is physically impossible. Every system has delays due to network transmission, computation, and storage.

But great System Design makes latency invisible—hiding it through smart architecture, predictive techniques, and real-time processing.

So how do you build a system that feels instant ... even when it isn't?

That's what we're exploring today. In this newsletter, we're breaking down:

• What zero latency really means (and why it's often misunderstood)

• 6 key System Design principles for real-time responsiveness

• Techniques to reduce latency

• Real-world examples from finance, gaming, and streaming

• Biggest trade-offs and challenges in low-latency systems

Let's dive in.

What are zero latency systems?

At their core, zero latency systems deliver responses or actions in real time, where the delay between user input and system response is unnoticeable.

This is the foundation of real-time communication, where even the slightest delay can disrupt the flow of information and break the illusion of immediacy.

This is an important distinction between perceived zero latency and actual latency. Zero latency still incorporates actual latency caused by technology limitations, like how long data travels through networks, is processed by servers, and returns a response.

But smart System Design can hide it by anticipating user actions, preloading data, or using a real-time feedback mechanism. For example:

• Autocomplete suggestions in a search bar appear as you type, giving the illusion of instant processing.

• A streaming service starts playing a video immediately by buffering the first few seconds in advance. A live streaming system that feels instantaneous but involves physical delays, as shown below:

In other words, perceived zero latency is about designing systems that feel instantaneous, even when small delays exist under the hood. It’s less about eliminating the delay entirely (a physical impossibility) and more about creating a real-time communication experience where latency is unnoticeable.

Why does zero latency matter?

We can better understand the importance of zero latency with a real-world example that can be catastrophic otherwise.

Take the case of autonomous vehicles: imagine a self-driving car approaching a pedestrian crossing. The system has milliseconds to process sensor data, detect the pedestrian, and apply the brakes – failure to do so in real time could lead to massive consequences. In such scenarios, latency isn’t just a technical metric; it’s a matter of life and death.

In such scenarios, there’s no room for hesitation—no tolerance for latency. The expectation isn’t just speed; it’s immediacy. Systems must react as fast as the human mind can think, or even faster, seamlessly becoming an extension of human intent. It is important because:

• People are wired for immediacy. Delays—even as brief as 100 milliseconds—can disrupt focus, break trust, or lead to frustration.

• Latency is not just inconvenient in fields like health care, finance, and autonomous systems—it can be life-threatening or financially devastating.

• Zero latency systems make technology feel natural, blurring the line between human intent and machine response.

Now that we understand latency's significance, we should explore the key characteristics of zero latency systems.