Laravel Query Optimization with Eager Loading

When working with Laravel's Eloquent ORM, one of the most common performance killers is the N+1 query problem. It appears the moment you load a collection of models and then touch a relationship inside a loop.

The N+1 problem

$posts = Post::all();            // 1 query

foreach ($posts as $post) {
    echo $post->author->name;    // +1 query PER post
}

Load 50 posts and you fire 51 queries: one for the posts, plus one for every author. It is invisible in code review but deadly under load.

The fix: eager loading with with()

$posts = Post::with('author')->get();   // 2 queries total

foreach ($posts as $post) {
    echo $post->author->name;            // no extra queries
}

Laravel runs one query for posts and a single WHERE author_id IN (...) for all authors - 2 queries no matter how many posts.

Nested & multiple relationships

// Multiple relations
$posts = Post::with(['author', 'comments'])->get();

// Nested relations (dot notation)
$posts = Post::with('comments.user')->get();

// Constrain a relation with a closure
$posts = Post::with(['comments' => fn ($q) => $q->latest()->limit(5)])->get();

Load only the columns you need

$posts = Post::with('author:id,name')->get();

Selecting id,name keeps the payload small - just always include the foreign key (id) or the relation will not match.

Eager load after the fact

Already have the collection? Load relationships afterwards with load():

$posts = Post::all();
$posts->load('author');

Catch N+1 automatically

Enable strict mode in a service provider so lazy loading throws during development:

use Illuminate\Database\Eloquent\Model;

Model::preventLazyLoading(! app()->isProduction());

Key takeaways

• with() eager-loads upfront (2 queries); load() eager-loads an existing collection.
• Always eager-load any relationship you touch inside a loop.
• Use column selection and closures to load only what you need.
• Turn on preventLazyLoading in dev to catch N+1 before it ships.