Maybe I'm missing something, but PHP is not more efficient in that regard.
When you load a Python page, it is served by an in-memory process. If code is updated, the process is restarted, parsing the code and initialising the application, but it is done only once.
When you load a PHP page, it parses the code and initializes the app for each request. It then tears everything down after the request. There are less wasteful ways (most recent are app servers, just like in Python or other langs), but I'm not sure if those are widely used in local development. Even then, it’s same as Python, Node or pretty much anything else.
And of course, I’m not trying to diss on PHP here – it’s gotten pretty good recently. But reload on change is built in pretty much every app framework nowadays. It works out of the box and is negligibly fast. It’s not a good point to compare.