Cumulative Layout Shift (CLS) is where the layout of a web page unexpectedly shifts after the initial content loads and new content pops in. At its best, it’s a little inconvenient. At its worst, it’s an accidental click of a “BUY NOW” button that suddenly appeared under your mouse cursor after an ad loaded, resulting in an unwanted purchase.

It’s the little things that can make a big difference. While we announced significant product updates like Autofix and Metrics (to name a few) during Launch Week, we couldn’t cover everything. Over the past few months, we shipped updates to the core platform, improvements to the developer workflow, and a series of quality-of-life features. The sum of these small improvements add up to big updates across Sentry that help make your production issues even more debuggable.

When cloud service providers first started popping up, many developers were “wowed” by being able to spin up and scale all kinds of infrastructure to deploy their web applications on demand. However, big-box cloud service providers are often complex to use, scaling out is expensive and default monitoring solutions are not very insightful. Besides, we are spoiled developers, and we expect things to be easy.

Recently, I improved all my homepage Core Web Vitals by focusing on improving just one metric: the Time to First Byte (TTFB). All it took was two small changes to how data is fetched to reduce the p75 TTFB from 3.46s to just 704ms. In this post I’ll explain how I found the issues, what I did to fix them, and the important decisions I made along the way. (And don’t worry, I’ll break down “p75” and “TTFB”, too!)