[jasim]

The `track by` feature alone wouldn't solve Angular performance problems if you are rendering a large dynamic table.

Every `ng-*` and text interpolation using `{{ }}` will add one binding per usage. This can add up quite fast and easily cross the sweet spot of 2000 bindings per page (http://stackoverflow.com/questions/9682092/databinding-in-an...).

Large grids are not an ideal use case for Angular, and I like the approach of using React/Mustache or even direct DOM manipulation inside an Angular application when performance is critical.

[GamblersFallacy]

I've build a large custom dynamic table for a real-time datamining web app, didn't have any performance issues because i used 'track by'.

The 2000 sweet spot comment from SO was based on angular 1.0.1, which didn't have 'track by' & is approx 1/10 the speed of angular now.

Look @ the updated jsperf digest test, from the SO answer, for angular 1.0.1 vs 1.2.14 http://jsperf.com/angularjs-digest/37