I have this simple api and the first time i make a request with postman it sends a response then it keeps loading forever. It stall the whole application. (Even if i do a GET request it's the same)
i think i create a fresh installation of laravel and then test it without doing anything go to the home page, hit fresh on your browser couple of times... and see if you get the same thing..
without knowing what you have done with your laravel installation we cant help you - github repo would be better..