Efficient way of User Management and User Sign Up modules in Ionic Framework /Angular JS??

I planned to take up an mobile application (Hybrid)not native using Ionic framework reason I opted ionic it supports Angular Js,Of course it was built on it. Regarding front end these are technologies i selected.I need some data to come from server so for that I am developing and API using PHP Laravel Framework.So,I am going to make $http or $resource calls over my API and get to the data.

So,I want my APP should very fast in User SignUp and SignIn process.So,I am thinking is there any way another alternative from AngularJS , Ionicframework and Phonegap side to manage User Signus and login .And main data I will get from my Laravel API.Why I am thinking of alternative because I got some views from co-developers that the app is going to slow if any backend API is used for User Signup and Logins.Can,I go head with Backend API or is there any alternative??