how to get users with booking count in laravel without using withcount because there is a bad performence with large database

The bad performance is not coming from using withCount but rather from when you do ->get() because you are trying to do that for ALL the users in the database. So a better performance will be if you paginate your results:

User::withCount('bookings')->paginate(10);

Very well documented here https://laravel.com/docs/8.x/pagination

You need to review the sql query and make sure you have the correct indexes in place.

Do you really need the bookings count for every user?

If so, a better solution might be Booking::groupBy(user_id)