I can testify to this, we use appcache for our HTML5 game and it massively improved load times. However, if you are going to use it, be absolutely sure you know

I can testify to this, we use appcache for our HTML5 game and it massively improved load times. However, if you are going to use it, be absolutely sure you know what you are doing. There are easy ways to mess up and no going back if you do.