GNOME Shell 3.32 is expected to be released on March 13, 2019. This new release brings real performance improvements, making this heavy Linux desktop environment lighter. GNOME Shell is used by default on Ubuntu and many other Linux distributions.
The GNOME Shell desktop environment has long been quite heavy compared to other Linux desktop environments. As an Ubuntu news site OMG! Ubuntu! points out:
You see, the GNOME Shell office is often criticized as being a bit "heavy". People criticize it for their relatively large use of boot memory, CPU latency and user interface that often stutters or loses images when in use.
But it's better. These latest enhancements come from both the GNOME "upstream" project and Canonical, the company behind Ubuntu. Georges Stavracas, a developer who has worked hard, exposes many technical details on his blog. A number of improvements result in improved throughput, smoother boot animations, and faster icon loading times. Work is also underway to reduce the use of the graphics processor.
Daniel Van Vugt from Canonical has also worked extensively on the performance of GNOME Shell. These fixes are not just for Ubuntu. They are integrated into the GNOME project and each Linux distribution will benefit. Linux news site Phoronix exposes most of the problems it's working on, but a lot of that boils down to reduced CPU and GPU usage. GNOME Shell is getting thinner and faster.
These improvements will be available in GNOME version 3.32.0, which should be available on March 13, 2019. But you will not get it. You will have to wait for your Linux distribution to send the new GNOME, often as part of a new version. For example, GNOME 3.32.0 will be included as part of Ubuntu 19.04 "Disco Dingo," The release is scheduled for April 18, 2019.