Currently webrender only works on nightly builds unless you have NVIDIA hardware on Windows 10 (not considered mature enough on other hardware/platforms yet).
But to enable it you turn on gfx.webrender.all in about:config.
For NVidia/Win10 users, is it in Stable, or only the beta channel? I have that configuration available but I still don't see the gfx.webrender.all key in about:config.
The "gfx.webrender.all" about:config preference to enable WebRender is only available in Firefox Nightly (not Beta or Release channels). The WebRender code exists in Beta and Release and might be randomly enabled for A/B experiments.
Going by this bugzilla thread it seems like it should be in stable. But maybe they changed it back.
Though the hardware requirement is actually NVIDIA desktop hardware on Windows 10, i.e. laptops are currently excluded. Which is implemented by checking if your computer has a battery.
Yup, this is an NVidia GTX 1080Ti on a desktop, should've been fine. Based on the other response it looks like the toggle is only on Nightly in Windows too, they're only doing random A/B tests on the other channels. Too bad.
A little OT: How do you use nightly? Do you have a cron job that downloads it? Do you download it every day? Do you only occasionally download it? Or is there some other way? I'd love to use it more but last I checked they didn't offer auto-updates to it.
You download the nightly installer from mozilla's website, and then it bugs you to "Restart to update" everyday. I run nightly on many of my systems, but I don't update every day
