Dependency injection in controllers in Laravel - Performance & Optimization

Performance: Dependency injection in controllers

MEDIUM IMPACT

This affects the server-side response time and memory usage, indirectly influencing page load speed by optimizing controller instantiation and reducing unnecessary object creation.

Injecting services into controllers for handling requests

Laravel

<?php
class UserController extends Controller {
    protected UserService $service;
    public function __construct(UserService $service) {
        $this->service = $service;
    }
    public function index() {
        return $this->service->getAllUsers();
    }
}

Injecting the service once via constructor avoids repeated instantiation, reducing CPU and memory overhead.

📈 Performance Gainreduces server CPU usage and memory allocation per request, improving response time

Injecting services into controllers for handling requests

Laravel

<?php
class UserController extends Controller {
    public function index() {
        $service = new UserService();
        return $service->getAllUsers();
    }
}

Creating a new service instance inside each method causes repeated object creation and increases memory usage per request.

📉 Performance Costadds unnecessary CPU and memory usage per request, increasing server response time

Performance Comparison

Pattern	DOM Operations	Reflows	Paint Cost	Verdict
New service instance inside method	N/A (server-side)	N/A	N/A	[X] Bad
Constructor dependency injection	N/A (server-side)	N/A	N/A	[OK] Good

Rendering Pipeline

Dependency injection in controllers happens on the server before the response is sent. Efficient injection reduces server processing time but does not directly affect browser rendering stages.

→Server Request Handling

→Controller Instantiation

⚠️ BottleneckRepeated object creation in controller methods increases server CPU and memory usage.

Optimization Tips

1Inject dependencies once in the controller constructor to avoid repeated object creation.

2Avoid creating service instances inside controller methods to reduce CPU and memory overhead.

3Efficient dependency injection improves server response time but does not directly impact browser rendering.

Performance Quiz - 3 Questions

What is the main performance benefit of using dependency injection in Laravel controllers?

A Improves browser paint speed

B Decreases DOM node count

C Reduces repeated object creation and lowers server CPU usage

D Reduces CSS selector complexity

DevTools: Network

How to check: Open DevTools, go to Network tab, reload the page, and check the server response time for controller actions.

What to look for: Look for faster server response times indicating efficient controller processing.