Um, its about your JavaScript...

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Discover the importance of performance budgets, RUM metrics, and CPU time tracking in optimizing website performance and user experience, and learn how to overcome common challenges with third-party content and JavaScript framework Playwright.

Key takeaways
  • We’re all in the trust tree together, focusing on the performance of our sites.
  • Measuring the performance of a site with RUM (Real User Measurement) metrics is more accurate than synthetic testing.
  • The number of JavaScript calls on a page has doubled over the past 7 years, from 5 to 12.
  • Tracking CPU time and blocking CPU time is important, as it affects user experience and business metrics.
  • A performance budget is a useful tool to track and analyze the performance of a site.
  • There is no single “unicorn” metric that measures everything; instead, we need to use a combination of metrics to understand the performance of a site.
  • Tracking FID (First Input Delay) and animation frame completion rate are important metrics for measuring user experience.
  • Using third-party content can have a significant impact on page load times, and budgeting for performance is essential.
  • Measuring the performance of a site with business metrics, such as conversion rate, is important for understanding the impact of performance on the business.
  • It’s important to keep in mind the limitations of different metrics and to validate them against business metrics.
  • A show of hands revealed that many attendees have reported on performance issues related to third-party content.
  • The JavaScript framework Playwright has a built-in performance timing API.
  • Performance budgets are supported in Google Lighthouse, Webpack, and other tools.
  • Mobile devices have gotten better, but even the best mobile devices have CPU thresholds that affect performance.
  • Measuring the performance of a site with CPU metrics, such as CPU idle time, is important for understanding how CPU-intensive scripts are affecting the site.