Is it possible to run cakePHP application and reactPHP as its web-server? I heard a huge performance gain by using reactPHP. However, I have not seen anyone have leverage on existing matured PHP framework such as cake.
Yes, it's possible.
We've implemented a Bridge for PHP-PM (based on ReactPHP) here https://github.com/CakeDC/cakephp-phppm
The plugin manages the bootstrapping and handling of an application request, and some experimental benchmarks proved that, in specific applications, it would provide a substantial performance boost (2x requests/second).