The latest release of Firefox (Firefox Quantum) is claimed to be twice as fast as its predecessor whilst remaining extremely light on resource use.
Private browsing and Tracking Prevention are available to enhance security and access to Pocket is built into the URL field for convenient archiving of interesting content. Most, but not all previous add-ons and extensions remain compatible. Sadly for me, although access to iCloud Mail and Calendar services still works the iCloud drive remains unaccessible.
I like the updated look of the browser and in the screenshot above I am using an Arc Theme and have removed the Bookmark Toolbar, accessing these via the “Bookmarks Toolbar Menu” addon. This keeps the browser header size to a minimum.