New
#890
Tab loading gets a bit faster...
Nightly 59.0a1 (2018-01-12) adds a new feature dubbed "Tab Warming"
Nightly will start loading a link in the background as soon as you hover your mouse cursor over that link so that when you click the link, the tab will load faster.
The feature is disabled by default, however, if you want to try it, set the browser.tabs.remote.warmup.enabled entry in about:config to true.