Symfony 8.2 Introduces Compiled Event Dispatcher for Improved Performance

Symfony 8.2 introduces a compiled event dispatcher.

The framework shifts the processing of event listeners from runtime to the container compilation phase. Previously, the event dispatcher resolved and sorted listeners during request execution. That older process required repetitive lookups and sorting logic every time an event triggered.

The new implementation caches this work during service container compilation. When the application runs, it executes a pre-optimized version of the listener stack. This helps applications with a high volume of events or complex listener hierarchies because moving the heavy lifting to the build step shortens the time required to dispatch events.

Developers can use Symfony 8.2 without significant changes to their existing event listener registration process. The framework handles the compilation internally.