I’ve been asked how memory-hungry Ubuntu 26.04 LTS is on my customized installation. The lazy way, gnome-system-monitor (for which I needed to add the CTRL+SHIFT+ESC shortcut because there wasn’t any) shows 2.0 GB after a reboot, when no app is active and the system doesn’t check for updates (manually check for updates, apply them if available, then reboot):

With or without customization (Ubuntu already customizes it to some degree), GNOME surely isn’t the desktop environment of choice for systems with less than 8 GB of RAM. To compare it against KDE and XFCE as live sessions from ISO files launched from Ventoy, I chose the following procedure:

  • I launched the live session on the 2023 Acer that has 16 GB RAM (shared with the Intel video).
  • After the Xorg or Wayland session was up, I did not connect to the Wi-Fi to avoid having it check for updates. I also avoided any attempt at an automatic initial configuration in Ubuntu and Kubuntu.
  • To avoid the extra RAM taken by a GUI terminal, I switched to another virtual terminal using CTRL+ALT+F2/F3, then I logged in using ubuntu/kubuntu/xubuntu (no password) or demo/demo in MX.
  • Finally, I used free -h (and free for more precise values) for a quick estimate on RAM usage. (I didn’t need details such as those offered by vmstat -s.)

Some notes:

  • Different distros have different RAM policies regarding the allocation of shared, buffer, and cache. When RAM is ample, having larger buff/cache values actually makes the system more responsive.
  • Therefore, I considered that the used field is the only relevant value to be considered. The free and available fields bear little practical relevance.

The updated ISOs that I used:

The results:

Distrousedused (KiB)sharedbuff/cache
MX XFCE sysvinit1.2 GiB1,245,128134 MiB1.1 GiB
MX XFCE systemd1.3 GiB1,354,468146 MiB1.3 GiB
MX KDE sysvinit1.4 GiB1,458,000253 MiB1.1 GiB
MX KDE systemd1.5 GiB1,524,992251 MiB1.5 GiB
Kubuntu (Wayland)1.5 GiB1,635,736338 MiB6.9 GiB
Xubuntu (Xorg)1.6 GiB1,706,192244 MiB7.1 GiB
Ubuntu (Wayland)1.9 GiB2,036,848466 MiB9.1 GiB

Surprise findings:

  • Xubuntu is far less optimized than Kubuntu!
  • GNOME in Ubuntu isn’t that bad, after all, and it tends to use the RAM for kernel buffers and disk cache. But you need at least 16 GB of RAM (seen as 15 GB if shared with the video) to really benefit of such huge buffers and page cache.
  • MX doesn’t change its RAM policy on systems with plenty of RAM, remaining optimized for 4 GB.
Family Guy S24E08 at 07m38s
Family Guy S24E08 at 20m26s