http test taking to long to visit a url from application

I have an HTTP test that is visiting a users list:

public function testUserListById()
{
    $user = User::factory()->create();

    $content = $this->actingAs($user)
        ->json('get', route('users.list'))
        ->assertStatus(200)
        ->getContent();

    $content = json_decode($content, true);

    assertTrue(count($content) >= 0);
}

The problem is that when I visit the API in postman it takes 400ms to visit that but in my test when I run it:

PASS  Tests\Feature\Users\UsersTest
✓ user list by id                           1.78s  

Tests:    1 passed (2 assertions)
Duration: 1.99s

It takes 2 seconds to visit the page in the test. This is my base testClass:

use App\Models\User;
use Illuminate\Foundation\Testing\TestCase as BaseTestCase;

abstract class TestCase extends BaseTestCase
{
    use CreatesApplication;

    protected $seed = true;

    protected function setUp(): void
    {
        ini_set('memory_limit', -1);

        parent::setUp(); 
    }
}

This is not exactly the solution for you, but I will "beautify and correct" your code a little bit:

public function testUserListById()
{
    $user = User::factory()->create();

    $this->actingAs($user)
        ->json('get', route('users.list'))
        ->assertOk()
        ->decodeResponseJson();
}

Here decodeResponseJson() will automatically give you an error back if it was not able to decode it. Have in mind that it is not asserting if it has content, just if it was able to decode it.

See also that I have used assertOk instead of assertStatus(200), there are available methods to assert some statuses, it is "easier" or more readable once you get used to them, they are just helpers.

Why am I not checking the content? Because you should not count or assert if you got content back, but exactly what content you expect back, else the test is half done, it is incorrect as anyone could change something from the controller and your test will still pass, how can a test like that be usable?

Super personal recommendation, do not add ini_set('memory_limit', -1);, if you have to do so, you are not correctly testing something or part of your code is absolutely not performant at all (a massive red flag), so you should see which test is destroying your memory and fix it. It is a subtle code smell/red flag.

Now, related to your issue, I am 99% sure you have a HUGE amount of migrations or one migration is doing a lot of work, so when you use RefreshDatabase trait, you can see it is only run once, then any action done in the database is just a transaction, so you only have the schema without content for each test (that is performant compared to migrating for every single test).

How can you know if this is the issue? You can add simple logging:

public function testUserListById()
{
    $start = now();

    $user = User::factory()->create();

    $this->actingAs($user)
        ->json('get', route('users.list'))
        ->assertStatus(200)
        ->decodeResponseJson();

    $end = now();

    dump($end->diffInMilliseconds($start));
}

You will see a number like this: 1 // tests/Feature/ExampleTest.php:36 that was the dump, showing it took 1 ms to run the test. If the test is super fast, then the migrations are taking a long time.