How $compileProvider.debugInfoEnabled set to false improve performance in angularjs 1.3?
These classes that are added to your DOM elements are directives (directive can be elements, attributes, classes, or comments).
When angular is compiling the DOM and hits a directive it then runs through that directives logic to change, manipulate, update, or do whatever task it is that the directive is asking angular to do.
For example it will take your ng-repeat directives and build out multiple DOM elements accordingly.
By removing these directives (classes like ng-scope & ng-isolated-scope) angular will not stop at these locations and execute logic. Because of this the performance increase is achieved.