The speed seems the same for light browsing, probably even better with Firefox because ublock origin is supported 100% from the first to the last API, and works as gorhill intended.
I think the problem with firefox is the heavy rendering, streaming and battery life. Laptops really get hot with Firefox, try to stream twitch or long youtube sessions and watch at your battery percentage, try to play an online game browser and see the fps differences with Chrome.
Gecko core engine has been a little bit abandoned. Mozilla doesn't have the same number of users and CAN'T have the same funds of the Chromium project obviously, but this is also the result of really bad choices in the last few years.
I hate to say that Chrome is better in everything: temperatures, efficiency, speed, battery life, with an exceptional management between light and heavy workloads. It updates seamlessly, never crashes, very rugged and oiled software without hassles. Who says chrome is bad just didn't use it recently.
Safari? Can't trust it, no APIs, UI very bugged. Without discussing WebKit engine and website compatibility, it seems to me an economy class piece of software, not curated nor tested enough. I guess even in apple don't trust it that much.