why not use $digest instead of $apply?

[MaestroJurko]

Why not use $digest in scroll, it is faster then $apply, but you cannot use the new setting latch, because that slows it down.

       if (updateInnerCollection()) {
            $scope.$digest();
            // $scope.$apply();
            $scope.$broadcast('vsSetOffset-refresh');
      }

[jramoyo]

I agree. For large applications, the scroll performance degrades significantly when using $scope.$apply().

From AngularJS Batarang:

$scope.$apply()

$scope.$digest()