As you may have read many times, Gnome 3.34 brings much improved desktop performance. In this article we will describe some of the improvements contributed by Canonical, how the problems were surprising, how they were approached and what other performance work is coming in future.

from https://discourse.ubuntu.com/t/boosting-the-real-time-performance-of-gnome-shell-3-34-in-ubuntu-19-10/13095