New York Times Store
I worked on New York Times Store more than a year as a dedicated developer. In the beginning Company I work for got this project in really bad shape from after NYTimes store switched from previous developers since they lacked quality and it was noticeable that product is becoming worse and worse after each iteration.
About 6 months we fought bugs and legacy shit code, when we finally got project as stable as we could we got 2-3 months in our hands to do complete FE rework as we want it, with tools we want.
Result is quite awesome, css is 3 times smaller than it was, we got rid of Magentos prototype library and rewrote everything to jQuery, cleaned up templates, added best optimisation practices, made js completely detachable.
Store is completely responsive, with some smart solutions how to optimise mobile experience. It is cached by varnish, so regular landing pages loads extremely fast, with good connection content appears below 1000ms, which even by nowadays standards is freaking fastView live version