Version 61.0a1, first offered to Nightly channel users on March 12, 2018
Firefox Nightly gets updated every day and as a consequence, the release notes for the Nightly channel are updated continuously to reflect features that have reached sufficient maturity to benefit from community feedback and bug reports. Features listed here may or may not make a final release of Firefox.
In addition to these release notes, you can follow ongoing development on our @FirefoxNightly Twitter account as well as read our Nightly Blog.
Tab warming was enabled for Nightly making tab switching more efficient in some cases. You can learn more about Tab Warming in this article