Tests by Google and Bing have shown that there are performance benefits to caching assets in localStorage (especially on mobile) when compared to simply reading and writing from the standard browser cache. This project is currently working on replicating these tests in the public so that we have definitive statistics on whether this is true.Steve Souders says:
We believe that in time, once implementers have optimized localStorage, it will become more feasible to use cross-browser.
Bing and Google Search make extensive use of localStorage for stashing SCRIPT and STYLE blocks that are used on subsequent page views.
Are Bing and Google Search onto something? Yes, definitely.
As I pointed out in my previous post, this is another example of a performance best practice that is used on a top mobile site but is not in the recommendations from Page Speed orYSlow.