PHP is pretty unusual in comparison to most web platforms nowadays as it runs each request in an isolated process. Web development in other languages is instead based around a long lived set of processes, which serve multiple requests.
That model has advantages in that it is very easy to cache data in process, and should be simpler in theory to get good performance as all code can be loaded into memory once during startup. Autoloading therefore goes away. There are userland implementations like PHP-PM, but I think it good to have an official way of running code in this way in php 8.
