What is performance engineering: A Gatling take

Source: Dev.to

Modern performance engineering: Why most teams don’t have performance problems — they have architecture problems

If you spend enough time around engineering teams, you start noticing a strange disconnect. Systems are built in isolated branches and tested in controlled staging environments, then deployed with crossed fingers and optimistic dashboards.

From there, they’re expected to withstand the chaos of real users, unpredictable traffic, and a production environment that behaves nothing like staging. Most teams don’t actually lack expertise or effort—they lack a realistic way of understanding how their systems behave under real‑world performance conditions.

Performance engineering is supposed to bridge that gap. But in many organizations, the only time performance enters the conversation is when something slows down in production. By then, the system is already struggling, dashboards are firing alarms, and everyone is trying to diagnose symptoms rather than understand causes.

This is usually the moment someone asks, “Didn’t we run a load test?”

And that’s where our story begins.

The night a load test passed and everything still broke

It was a typical launch night—the kind nobody admits is stressful until things go wrong. The team had done what they believed was proper performance testing: they wrote a load test, executed it in staging, reviewed the performance metrics, and saw nothing alarming. Charts stayed flat, latency behaved, and the environment appeared calm. There’s a comforting illusion that comes from green dashboards.

But staging environments are often polite liars.

Within an hour of deployment, production behaved differently. Response times started creeping up, then rising sharply. Error rates appeared. API clients experienced unexpected timeouts. The team gathered around monitors, trying to interpret what was happening. The first suspicion was obvious: the load test must have missed something. “But it passed yesterday,” someone said, as if passing performance tests guaranteed system performance under real workloads.

The issue wasn’t the test itself—it was the assumptions behind it. The load test didn’t simulate realistic concurrency patterns. It didn’t reflect actual data volumes. It didn’t account for a downstream dependency that behaved fine in staging but collapsed under production conditions. The test wasn’t wrong; it simply wasn’t engineered to expose the performance bottlenecks inherent in the system.

This wasn’t a load problem. It was an architecture problem that load testing revealed only partially.

What is performance engineering? (through a developer’s eyes)

Performance engineering is often defined in vague or academic terms, but at its core, it is the practice of designing, validating, and improving systems so they behave predictably under real‑world conditions.

It brings together architectural thinking, performance testing, performance optimization, performance monitoring, and an understanding of how applications behave under genuine load.

In practice, performance engineering requires:

• Architectural awareness
• Realistic performance testing
• Continuous performance monitoring
• Meaningful performance metrics
• Profiling and performance analysis
• Willingness to challenge assumptions

It is closely tied to developer experience. Developers are the ones writing the code, making architectural decisions, and defining behavior. They’re also in the best position to prevent performance issues early—if the process supports them.

This is why test‑as‑code matters. When performance tests live in version control, run in CI/CD, and evolve with the application, they become part of everyday engineering rather than a late‑stage activity.

Tools like Gatling Enterprise Edition support this shift by turning load testing into a developer workflow instead of a separate QA task. This is performance engineering integrated into development, not bolted on afterward.

The myth of performance issues

It’s easy to believe that performance issues stem from “too much traffic” or from unexpected spikes in requests. It’s a comforting conclusion because it frames performance problems as external events rather than internal decisions. But systems don’t behave differently under load; they reveal their true nature.

• A synchronous call chain looks harmless in development and becomes a bottleneck under concurrency.
• A database query that operates fine on small test datasets becomes slow with realistic volumes.
• A microservice architecture that communicates too frequently performs well in isolation but degrades under load.

These performance issues don’t appear suddenly. They emerge when the environment becomes real enough to expose architectural weaknesses. Load testing doesn’t create performance problems. It simply makes them visible.

Why performance engineering matters across your organization

When application performance degrades, the impact spreads quickly. Users notice slow interactions even when they don’t know why. Business leaders see lost conversions and higher abandonment. Developers get paged, often in the middle of the night. Performance engineers begin searching through logs, metrics, and traces. Quality engineers are suddenly responsible for analyzing scenarios they never had the tools or data to validate.

When performance engineering is practiced consistently, the opposite happens. Performance issues become rare. Performance bottlenecks are discovered during development instead of in production. Incidents decrease. Teams regain stability and confidence. Leadership begins viewing performance not as a cost but as a competitive advantage.

Everyone benefits when performance is engineered into the system rather than inspected at the end.

The real performance engineering lifecycle

If you ignore the PowerPoint diagrams and focus on how engineering teams actually operate, performance engineering follows a practical lifecycle that mirrors how systems evolve.

Performance requirements

Most teams skip this foundational step. Terms like “fast,” “scalable,” or “high performance” are meaningless until they’re converted into measurable performance requirements. Clear requirements shape architectural decisions more than any framework, language, or infrastructure. These requirements typically include:

• Latency targets
• Throughput expectations
• Concurrency limits
• Degradation thresholds
• Cost‑performance constraints

Architecture and design

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