I’ve written a few times about gccemacs (1, 2, 3) and what it means for the future of Emacs. The good news is that it’s being merged into the Master branch and with any luck will make its first official appearance when Emacs 28.1 is released.
In the mean time, the more adventurous can try things out by compiling the development version of Emacs 28 from its Git repository. Of course, Emacs 28 is still very early in its development cycle and is not stable. Still, if you just want to try it out or have a particular need for the speed boost, there’s no reason not to try it out.
Luca Cambiaghi really needs the speed so he’s compiled the macOS gccemacs repository for his everyday use. He gives a detailed explanation of his steps and the problems he found. If you’re on macOS and want to try out gccemacs, his post is a good resource. I’d be hesitant to use it for anything other than experimentation or tire kicking—although Cambiaghi appears to be using it as his working version—but if you want to see what all the excitement is about, follow Cambiaghi’s recipe to try it out. He also has something to say about Doom Emacs so if you’re interested in Doom, you should also check out his post.