When navigating to a new page in the web browser, the front page of the open page is excluded in your computer memory. Cache saved images and other data, but if you press back, your browser will reload the page. Google Chrome developers are experimenting with the new cache / backwards to immediately load the previous page.
Simply clicking on the link on the page, this feature will freeze the home page in the memory. If you press back, the locked page will be restarted immediately. Chrome estimates that "19 percent of all browsing could be improved" in Android version.
It should be noted that it is far from the browser that is experiencing this Chrome concept. Firefox backtrack / back cache uses part of Firefox 1.5 (since its release in 2005), but it seems that HTTPS has disabled. Safari has also changed since 2009.
This feature is still at the beginning, and there are problems with security and issues that are compatible with iron. At the very least, it's very easy to find nowadays many RAM movements in absurd amounts of RAM.