Google Chrome developers are experimenting on a new ‘back/forward cache’ that would make loading the previous page instant since if you close a web page on the browser, it has to load most of the page again which is time-consuming.
This means when you click on a link on a page, this feature will keep the original page frozen in memory. If you press back, the frozen page is instantly resumed. The Chrome team estimates this could “improve performance up to 19% of all navigation” on the Android version.
This doesn’t mean that Chrome is the only browser to be working on this, Firefox back in 2005 has used back/forward caching to some extent since Firefox 1.5, but it seems to be disabled for HTTPS sites. Safari has also had a variant of it since 2009. Since this feature is still in the early stages, and there is still security and compatibly issues to figure out, there’s no timeline for the rollout of it yet.