https://www.bennadel.com/blog/2807-using-rootscope-emit-as-a-performance-optimization-in-angularjs.htm
Using $rootScope.$emit() As A Performance Optimization In AngularJS
Ben Nadel looks at using $rootScope.$emit() as a possible performance optimization when you a Service needs to communicate with a directive in AngularJS.
performance optimizationusingrootscopeemitangularjs