CPU usage has gotten a complete overhaul. You should now see far lower CPU usage when screen sharing, without a noticeable performance drop.

Additionally, if you want to remove CPU throttling and get all the raw power of your computer, disable the new option from within Settings, and you'll get full frame rate screen sharing (useful if you're screen sharing a video, for instance).

Scrolling has been improved (particularly with Windows and Linux).

Two major causes of frozen screen sharing have also been fixed.