The new client is some weird plugins/services based architecture. Things that'd barely warrant their own class in a boring OOP-based UI framework are instead now "isolated" services. The reality of this isolation being that if one piece breaks, the whole UI becomes unusable anyways. Dozens of things that in another app would've been just a simple synchronous call now behave like remote procedure calls and messages, forcing all the complexity of distributed systems into a local application for no reason.
That's why it runs like ass, breaks if you look at it wrong, and your CPU draws more power when using the client than when playing the game at 200FPS.
It's not the only option, but it's the most mature with the largest amount of docs + stack overflow questions, so it's a "safe" choice.
If you peek into the native resources files of most games/desktop apps, you'll find a good portion of them bundle + use the CEF dll.
The desktop app was originally a native C++ app, but they switched to CEF around 2011-2012. (It caused a very noticeable drop in performance!)
news to me. Been using steam since it launched. Never noticed it being sluggish
No shortage of games using it for in-game browser stuff, too.
Before that I was closing both and playing a game of roulette. By the the time my game was working, I may have already been reported for being afk and the game ended. Edit: other bugs have included starting to download the game and then signing in afterwards (their UI doesn't stop you) and then download progress disappearing, perhaps hanging, and you having no way to know it for a 40gb file unless over an hour has passed and you check disk size and then realize the client doesn't know how to load it. Start over and do a fresh install again, clear cache etc because their cache of the client still thinks somethings being downloaded even though it's not. Also having chat permanently off, results in weird glitches with friends requests and being unable to add new friends.
Horrible experience. But since the game is so optimized for addiction and dark patterns these days, and sunk cost, its a game I find myself returning to every once in a while.