Update: PiMix has been discontinued since October 2021 due to very few downloads, and the release of Ubuntu 22.04. The Ubuntu Gnome desktop on 22.04 runs well on Pi 4 without any lag, and it is no longer necessary to use a lightweight desktop like Xfce.

Please try the official Ubuntu desktop if you need an alternative.

PiMix 21.10 is now available based on Ubuntu 21.10 (Impish Indri).

PiMix is a remixed version of 64-bit Ubuntu for the Raspberry Pi 4 that is optimized for desktop use.