Is Lubuntu 20.04 still the most lightweight Ubuntu flavour?
We know there are graphical interfaces more lightweight than LXDE, but among the Ubuntu flavours, Lubuntu has been the highlight in this point for several years. Since it switched to LXQt I wonder whether that might not be the case any more, let’s see.
There are a set of resources that can be considered in order to compare how lightweight a distro is, the first one we think about is memory usage, of course, but there is also storage usage, boot time, cpu usage while in idle, number of processes launched and standing in background, etc.
I have installed the three lighter flavours in a VM: Lubuntu, Xubuntu and Ubuntu MATE, in order to compare them in some of the aspects mentioned above, not all of them, since some are not easily measurable, such as boot time and cpu usage, as it can vary depending on the time, network latency, storage and memory speed, services on the host and others abnormalities. And I achieved the following result:
+--------------+--------+---------+----------+---------+
| Flavour | Memory | Storage | Packages | Process |
+--------------+--------+---------+----------+---------+
| Lubuntu | 332M | 5.8G | 1776 | 151 |
| Xubuntu | 424M | 6.0G | 1578 | 161 |
| Ubuntu Mate | 435M | 6.1G | 1652 | 168 |
| Xubuntu Core | 351M | 3.5G | 1139 | 153 |
+--------------+--------+---------+----------+---------+Here the Xubuntu Core is not an official flavour, but rather a community attempt to clean Xubuntu from unnecessary packages, some of them are services, so you might miss some feature, if so just install what you need, it also comes with no browser in order to let you choose the one of your taste.
It is crucial to mention that when using Lubuntu you must have both Qt and GTK libraries, because it still have some native GTK softwares, and with other flavours you mostly don’t need Qt at all, unless you install some applications that requires it and doesn’t use AppImage, but you can always rely on containers to set them in a sandbox in that cases. I would say it is almost impossible to get rid of GTK, but you can live pretty well without Qt.
Conclusion
Between the official flavours, Lubuntu is still leading in terms of memory usage, but it requires more packages, in order to maintain Qt libraries together with GTK ones, so it will mostly have more dependencies to fetch during updates.
It really impressed me, since Qt was known as being resources’ gluttonous and had issues with memory leak (QTBUG-25279, QTBUG-59865, etc). I really thought it would eat more memory.
Lastly if you don’t mind using an unofficial flavour, I strongly recommend you adopting Xubuntu Core and installing only the packages you use (that would be the best lightweight scenario).
Appendix
Detailed component memory usage table:
+----------------------------+---------+---------+
| Component | Lubuntu | Xubuntu |
+----------------------------+---------+---------+
| DM (sddm x lightdm) parent | 14.0M | 7.2M |
| X | 60.9M | 71.0M |
| DM child, as login manager | 13.8M | 7.2M |
| session (lxqt x xfce4) | 37.8M | 53.0M |
| screensaver (x x xfce4) | 5.1M | 25.3M |
| WM (openbox x xfwm4) | 28.5M | 79.1M |
| panel (lxqt x xfce4) | 85.8M | 29.7M |
| desktop (pcmanfm-qt x xf) | 76.0M | 38.0M |
| notify (lxqt x xfce4) | 37.9M | 17.6M |
| tray (nm-tray x nm-applet) | 38.6M | 31.6M |
| PM (lxqt x xfce4) | 36.6M | 15.0M |
| settings (lxqt x xf) | 35.9M | 22.4M |
| lxqt-runner | 45.9M | - |
| file manager (thunar) | - | 22.9M |
| xiccd (colord bus) | - | 8.9M |
| wrapper (sum) (shared-lib) | - | 248.8M |
+----------------------------+---------+---------+P.S.: I am looking forward to wayland, at the beginning it will be hard to coexist without X, even with wayland it will have to support legacy X dependent applications, the day we would have been able to use wayland without X I think we would achieve the best performance with the lowest footprint.
