This feature requires WebRender to be enabled, according to the release notes:
https://www.mozilla.org/en-US/firefox/70.0beta/releasenotes
WebRender is automatically enabled for certain browser configurations:
https://wiki.mozilla.org/Platform/GFX/WebRender_Where
Anyone without these configurations can force WebRender on by setting gfx.webrender.all to "true" in about:config.
This feature requires WebRender to be enabled, according to the release notes:
https://www.mozilla.org/en-US/firefox/70.0beta/releasenotes
WebRender is automatically enabled for certain browser configurations:
https://wiki.mozilla.org/Platform/GFX/WebRender_Where
Anyone without these configurations can force WebRender on by setting gfx.webrender.all to "true" in about:config.