Why ‘Good’ Performance Metrics Might Be Killing Your Business

Performance testing, as a science, is traditionally more focused on measuring the maximum load the application can take and measuring the system latency with different loads reflecting production volume. Once the tests are complete system performance metrics are measured and shared with the product team. Also, these metrics are continuously monitored even after the application goes live.

Below is an example of how these metrics may look:

-Response times under 200ms? Great!
-99.9% uptime? Excellent!
-Can handle a million api calls with 2s latency? Extra Ordinary!

Any software team would love to have the above metrics. However, consider a situation where these meticulously tracked metrics are giving are a direct contradiction to user metrics in a case where users keep abandoning your app.

The Metrics Mirage

Traditional performance testing has long focused on response times, throughput, max load that can be withstood by application, and error rates. These metrics aren't wrong—they're just insufficient for modern-day systems.

Consider an application that loads fast but frustrates users with an unintuitive interface. Or consider an e-commerce application that has lightning-fast response times but still loses customers at checkout due to a convoluted payment flow. Your metrics dashboard shows green across the board while your business bleeds users. The worst part? Nobody in the IT team knew about this. As someone who assures quality, it is important to look beyond these numbers.

Beyond the Numbers Game of Performance Metrics

Today's application landscape demands a more nuanced approach. Here's what performance testing should cover for a wholistic approach:

User Experience as the North Star

Metrics based on response times and error rates tell you if pages load quickly, but does not capture if users were able to accomplish their goals efficiently. Supplement traditional testing with:

• User journey simulations to measure task completion rates

• Frustration indicator metrics to track rage clicks and form abandonment

• Other Perceived performance measurements that may differ from technical performance Ex: The successful customer conversion ratio

  Business Impact Assessment

  Application Quality & Performance isn't just a technical concern; it's imperative to business performance. This impact can be measured with the below methods using A/B testing or charting a graph based on existing data

  Ex: amount of revenue with an extra 10ms of load time.

  • Revenue impact analysis of performance degradations
  • Conversion rate correlation with performance fluctuations
  • Customer retention metrics tied to system performance

  System Resilience Over Non-Ideal Conditions

  Perfect test environments very rarely match what happens in production.

  Ex: Think of Prime day where the production load might be 10 times more than usual and there are brief spikes at the start or end of the day that have the potential to even exceed 20-30 timesthe usual load.

• Chaos engineering to observe test system behavior under unexpected conditions

• Capture performance under resource constraints (what happens when you're at 80% capacity?)

• Recovery time objectives after performance incidents

  The Holistic Testing Blueprint

  To make a paradigm shift to a more comprehensive approach, there is a need to completely rethink your testing strategy:

  1. Definition of success beyond metrics: Start with business and user experience goals, then determine which metrics support those objectives.

  2. Test real-time user scenarios: Move beyond isolated endpoint testing in isolation, to full user journeys that mimic actual behavior patterns.

  3. Incorporate qualitative feedback to Testing Strategy: User interviews and satisfaction surveys provide user context that performance metrics alone cannot provide.

  4. Measure business outcomes: Track measures that are key KPIs likeconversion rates, cart abandonment, and other business metrics alongside technical performance indicators.

  5. Test system adaptability: Measure whether the system can handle sudden traffic spikes, third-party service failures, or network degradation gracefully.

  Conclusion - Making the Shift

  This holistic approach doesn't mean the current metrics need to be abandoned. It just needs enrichment with additional user and business context. For Ex: Response time matters, but response time during peak shopping hours for your highest-value customers matters more. Performance testing has to evolve from being a mere checklist to a guide that can adapt applications to support business-critical use cases. The most effective teams recognize that true performance optimization happens only when both technical and business teams collaborate effectively to agree upon the key success factors and work towards the same. The metrics dashboard isn't lying to you—it's just telling a fraction of the story. It's time to demand the full narrative.

  References

  1. Molyneaux, I. (2023). The Art of Application Performance Testing: From Strategy to Practice. O'Reilly Media.
  2. Nielsen, J. (2020). "Perceived Performance: The Only Performance That Really Matters." Nielsen Norman Group. https://www.nngroup.com/articles/perceived-performance/
  3. Humble, J., Molesky, J., & O'Reilly, B. (2021). Lean Enterprise: How High Performance Organizations Innovate at Scale. O'Reilly Media.
  4. DeCandia, G. et al. (2022). "Holistic Performance Testing at Amazon: Beyond the Numbers." ACM Queue, 20(2), 1-26.
  5. Allspaw, J. (2019). Web Operations: Keeping the Data On Time. O'Reilly Media.
  6. Bondi, A. B. (2021). "Incorporating Business Metrics into Performance Engineering." IEEE Software, 38(4), 18-23.
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  8. Grigorik, I. (2023). High-Performance Browser Networking. O'Reilly Media.
  9. Winters, T., Manshreck, T., & Wright, H. (2020). Software Engineering at Google: Lessons Learned from Programming Over Time. O'Reilly Media.
  10. Forsgren, N., Humble, J., & Kim, G. (2018). Accelerate: The Science of Lean Software and DevOps. IT Revolution Press.