Extending CP makes requests 10x slower

I extended the CP to show reported posts in a community so admins can deal with those posts directly in the CP. As of now, I'm not even returning any data. But after implementing the basics, I noticed that all requests were significantly slower, across the whole page, not just the CP. So even regular Laravel routes took much longer to load.

Here is what I did:

In my AppServiceProvider I added this:

Statamic::pushCpRoutes(function () {
    Route::namespace('\App\Http\Controllers')->group(function () {
        require base_path('routes/cp.php');
    });
});

In my config/app.php I added this line:

App\Services\StatamicCPExtend::class

My StatamicCPExtend class looks like this:

use Statamic\Facades\CP\Nav;
use Statamic\Providers\AddonServiceProvider;

class StatamicCPExtend extends AddonServiceProvider
{
    protected $routes = [
        'cp' => __DIR__ . '/../routes/cp.php',
    ];

    public function boot()
    {
        parent::boot();

        $this->createNavigation();
    }

    protected function createNavigation()
    {
        Nav::extend(function ($nav) {
            $nav->tools('Community')
                ->route('emcommunity.users')
                ->icon('users')
                ->active('emcommunity')
                ->children([
                    $nav->item('Gemeldete Beiträge')->route('emcommunity.reports')
                ]);
        });
    }
}

The reports function in my controller looks like this:

public function reports()
{
    return view('cp.community-reports', [
        'title' => 'Community | Gemeldete Beiträge',
        'reports' => []
    ]);
}

After removing the above code, the pages load fast again.

I'm not able to locate the issue. I wouldn't care if the CP takes a bit longer loading (and not the actual website), so maybe this whole logic could be only applied to the CP. Would that be possible and if so, how?