• Set xdebug.mode to "develop,profile", and var_display_max_children, var_display_max_data, var_display_max_depth to either unlimited or very high.
• Install a DI container with Autowiring, such as DI52 or other one from your preference.

Create two classes Foo and Bar:

class Foo {
protected Bar $bar;

public function __construct(Bar $bar) {
$this->bar = $bar; // Maybe constructor promotion can also replicate it, but I didn't try.
}
}

class Bar {}

• Now build Foo, with $container->make(Foo::class);
• Now open the profile that was generated and see that a high memory and time was spent on Reflection
• Revert "var_displaymax" variables to defaults and try again, see that memory and time usage is normal
• Do so preferably on the context of a big codebase where lots of things happened before getting to that point of execution.