Optimizing Performance with Early Hints in Symfony 6.3

Introduction

The 6.3 version of Symfony continues to bolster the framework’s stature as an indispensable tool for PHP developers, introducing innovative features aimed at enhancing web application performance. One such feature is Early Hints, a recent and effective technique to optimize the perceived performance of websites and applications. In a world where every millisecond counts, adopting such optimizations can greatly enhance user experience and, consequently, the success of your application.

Understanding Early Hints

Early Hints are a technique allowing servers to inform browsers about resources (CSS files, JavaScript, web fonts, etc.) to preload while the server is still working on creating the response. Technically, Early Hints are an HTTP response with a status code of 103 that contains one or more HTTP headers listing the resources to load or connect to. This procedure allows browsers to start loading these resources or preparing for them, significantly improving the perceived performance of the website or application.

Implementation in Symfony 6.3

In Symfony 6.3, support for Early Hints was added via the sendEarlyHints() method defined in AbstractController. Here's an example code: