使用'use'或'include'实际上是否真的将PHP文件加载到内存中？ [重复]

Question

This question already has an answer here:

• When is a php include file parsed? 3 answers
• How does the PHP 'use' keyword work (in Symfony 2)? 2 answers
• How big of an impact does including PHP files have on performance? 2 answers

When I use use Class\Whatever or include 'Class/Whatever' (or require etc) at the top of a file before the file's Class is declared, does that file load the included file into memory at the time, or is it only loaded in and parsed when it needs to be (lazy-loading)?

I'm not finding any resource that mentions how this behaves or if it's optimized; I'd rather call the use or include when they're needed (inside the class when I want to instantiate the included class' object), but if the minimum necessary is already being done with this, then I'll keep them at the top of the file.

Tried moving the calls around but I'm not seeing any way to tell when they actually load or are compiled and parsed.

require 'baseClasses/Controller.php';
require 'vendor/autoload.php'; // Autoload.php is generated by Composer

use Lcobucci\JWT\Builder;
use Lcobucci\JWT\Signer\Hmac\Sha256;

Expected results are for the PHP engine to simply mark a use/include for loading and parsing when a line of code actually tries to do something with it. I can't tell what the actual results are other than my code just works, but I don't want unnecessary resources loading and parsing when they're not actually being used.

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