Ask which Linux desktop is the lightest and you’ll get an answer from a 2015 forum thread: LXDE, then Xfce, with GNOME and KDE as the heavyweights. The desktops have changed a lot since then, and so has what Ubuntu installs around them. We put the seven mainstream desktops that ship as official Ubuntu 26.04 flavours on identical VMs and measured them instead of guessing.
This is a desktop environment RAM usage comparison of GNOME, KDE Plasma, Xfce, LXQt, MATE, Cinnamon and Budgie, each installed from its flavour metapackage on the same Ubuntu 26.04 LTS base. For every desktop we recorded idle memory after login, the memory the session itself holds, time from kernel start to a working panel, and disk and package counts, plus a headless control so you can see what the desktop alone costs. If you are choosing a whole distro rather than a desktop, our Linux desktop distribution picks and the lightweight distros we tested for old hardware cover that side.
Current as of October 2026.
Desktop environment RAM usage at a glance
Ranked by idle RAM used, lightest first. “Desktop cost” is idle RAM minus the 427 MiB the same Ubuntu install uses with no desktop at all. RAM figures are medians of 9 samples over 3 cold boots, boot time is the median of 3 boots, and disk and package counts are single readings after install.
| Desktop (flavour) | Session | Idle RAM used | Desktop cost | RAM left for apps | Kernel to panel | Disk added | Packages added |
|---|---|---|---|---|---|---|---|
| LXQt (Lubuntu) | X11 | 745 MiB | 318 MiB | 3,165 MiB | 12.7 s | 4,638 MB | 1,337 |
| Budgie (Ubuntu Budgie) | Wayland | 806 MiB | 379 MiB | 3,104 MiB | 13.5 s | 4,935 MB | 1,339 |
| MATE (Ubuntu MATE) | X11 | 835 MiB | 408 MiB | 3,075 MiB | 14.3 s | 5,156 MB | 1,435 |
| Xfce (Xubuntu) | X11 | 888 MiB | 461 MiB | 3,022 MiB | 13.8 s | 4,981 MB (includes GNOME Shell and GDM) | 1,336 |
| GNOME (Ubuntu) | Wayland | 894 MiB | 467 MiB | 2,504 MiB (kdump takes 512 MiB) | 11.2 s | 4,151 MB | 1,006 |
| Cinnamon (Ubuntu Cinnamon) | X11 | 960 MiB | 533 MiB | 2,950 MiB | 13.7 s | 2,950 MB | 1,115 |
| KDE Plasma (Kubuntu) | Wayland | 1,209 MiB | 782 MiB | 2,701 MiB | 12.7 s | 5,462 MB | 1,640 |
| No desktop (control) | none | 427 MiB | 0 | 3,483 MiB | n/a | 2,475 MB used | 693 installed |
Three things stand out. LXQt is still the lightest, but the gap to Budgie and MATE is under 100 MiB. Xfce is no longer lighter than GNOME on Ubuntu: 888 MiB against 894 MiB, which is inside the run-to-run noise. And the stock Ubuntu GNOME install leaves you the least memory for applications of any desktop here, because it is the only flavour that reserves 512 MiB for kernel crash dumps.
Boot time barely separates them. Every desktop reached a running panel 11 to 15 seconds after the kernel started, and 18 to 24 seconds after the VM was powered on (measured from the Proxmox host).
How we measured it
Each desktop got its own VM on one Proxmox host (Intel Core i7-6700), cloned from the same Ubuntu 26.04.1 LTS cloud image: 2 vCPU with cpu=host, 4,096 MB RAM with ballooning pinned (min equals max), a 32 GB virtio disk and a 1280×800 display. The base system was fully upgraded first, then the flavour’s metapackage went on with its recommended packages, exactly as apt pulls it:
sudo apt-get install -y kubuntu-desktopSwap in ubuntu-desktop, xubuntu-desktop, lubuntu-desktop, ubuntu-mate-desktop, ubuntucinnamon-desktop or ubuntu-budgie-desktop for the others. Each VM logged in automatically to the flavour’s default session, and only one VM ran at a time during measurement. Here’s how each number was taken:
- Idle RAM used:
MemTotalminusMemAvailablefrom/proc/meminfo, read at least 300 seconds after the panel appeared, three times 30 seconds apart, on each of three cold boots. A warm-up boot ran first and was discarded. - RAM left for apps:
MemAvailableat the same moments. This is the number that decides when a browser tab pushes you into swap. - Session memory: the summed PSS (proportional set size) of every process owned by the logged-in user, from
/proc/<pid>/smaps_rollup. PSS splits shared libraries fairly between processes, so it does not double count like RSS does. - Kernel to panel: guest uptime minus the age of the panel process (
gnome-shell,plasmashell,xfce4-panel,lxqt-panel,mate-panel,cinnamon,budgie-panel), median of three cold boots. - Disk and packages added:
dfused space anddpkg-query -Wcount after the install and anapt-get clean, minus the same readings on the headless control.
Two things were changed on every VM so dialogs would not skew the numbers. First-run wizards (Ubuntu’s welcome wizard and Plasma Welcome) were marked as done, since a real user clicks through them once. Apport was disabled, because blueman-applet crashes at login on a machine with no Bluetooth adapter and Apport then opens a “System program problem detected” dialog over the desktop. We hit it on the first login of the MATE VM, and the crash report it left was /var/crash/_usr_bin_blueman-applet.1000.crash. On real hardware with a Bluetooth radio you are unlikely to see it.
This is a fresh, idle desktop with nothing open. A browser adds its own memory on top of whichever desktop draws the window around it. The numbers show the floor each desktop sets before you do any work.
1. LXQt (Lubuntu)
LXQt is still the lightest desktop environment on Ubuntu. It idled at 745 MiB used (732 to 758 across all nine samples), only 318 MiB above the bare system, and the user session held 353 MiB PSS. The panel itself is tiny at 34 MiB. The biggest single consumers were the desktop portal and blueman-applet at 36 MiB each, not anything LXQt-specific.
Lubuntu runs an X11 session, and the X server itself (running as root, so outside the session PSS figure) adds another 66 MiB. Lubuntu 26.04 ships LXQt 2.3 with SDDM as the login manager.
Where it falls short: it is the plainest of the seven, and you’ll want to tweak the Qt and GTK themes so mixed apps look consistent. If you only pick one desktop for a 4 GB laptop, this is it.
2. Budgie (Ubuntu Budgie)
Budgie was the surprise. It’s now a Wayland desktop running on the labwc compositor, and it came second at 806 MiB used (774 to 817), with a 414 MiB session. The compositor took 88 MiB and the dock 26 MiB, and the panel was just 22 MiB. The screen had locked itself by the five minute mark, so swaylock (35 MiB) is in that figure too.
Because labwc runs inside the user session, that 414 MiB already includes the display server. The X11 desktops above and below it pay another 54 to 90 MiB for Xorg on top of their session figure, which is why Budgie edges out MATE on total RAM. The tested build was budgie-core 10.10.2.
The catch: upstream’s attention has moved to Budgie 11 (a new QML panel and early work on Mir), so the 10.10 series now gets minor releases such as 10.10.3 in September 2026, per the Buddies of Budgie blog. If you want a modern Wayland desktop that is not GNOME or Plasma and still idles near LXQt, Budgie is the one. Debian users can get it too with our Budgie on Debian guide.
3. MATE (Ubuntu MATE)
MATE idled at 835 MiB used (818 to 855) with a 401 MiB session, so its own processes are almost as lean as LXQt’s. The largest were the Caja file manager drawing the desktop (54 MiB) and mate-session (39 MiB). The panel and its applets were 9 to 13 MiB each.
What pushes MATE above Budgie is the X server, which held 90 MiB here, the most of any X11 desktop we tested. Ubuntu MATE also autostarts the Evolution calendar alarm and data services (around 55 MiB together), which you can disable if you do not use a calendar.
The weak spots: X11 only, and the session manager in 26.04 is 1.26 while upstream has moved on to 1.28. For people who want the classic GNOME 2 layout and low memory, it’s still the standout.
4. Xfce (Xubuntu)
Xfce idled at 888 MiB used (867 to 942), essentially tied with GNOME. The Xfce components themselves are small: xfwm4 36 MiB, xfce4-session 22 MiB, xfdesktop 17 MiB. What fills the rest of the 469 MiB session is the Ubuntu desktop plumbing that Xubuntu now carries: IBus (70 MiB in its three biggest processes), the Evolution calendar services (38 MiB) and the GNOME LocalSearch file indexer (12 MiB). Outside the session, fwupd runs as root and holds another 29 MiB.
There’s a second catch if you add Xfce to an existing Ubuntu install. On our VM, apt-get install xubuntu-desktop with recommends also pulled in GNOME Shell and GDM, and GDM became the default login manager. Xubuntu’s own login manager is LightDM, so we switched it back with the exact commands below:
echo "/usr/sbin/lightdm" | sudo tee /etc/X11/default-display-manager >/dev/null
echo "lightdm shared/default-x-display-manager select lightdm" | sudo debconf-set-selections
sudo DEBIAN_FRONTEND=noninteractive dpkg-reconfigure lightdmRunning sudo dpkg-reconfigure lightdm on its own does the same job through a menu. Confirm which display manager will start on the next boot:
readlink /etc/systemd/system/display-manager.service; cat /etc/X11/default-display-managerBoth lines should name LightDM:
/lib/systemd/system/lightdm.service
/usr/sbin/lightdmAfter a reboot the VM logged straight into the Xubuntu session through LightDM:
What holds it back: the reputation for being light now belongs to the Xfce code, not to Xubuntu as shipped. IBus, the Evolution services and LocalSearch add up to about 120 MiB of that session, and all three can go if you don’t use them. On Fedora the picture is different, since its Xfce install does not carry Ubuntu’s defaults.
5. GNOME (Ubuntu)
Stock Ubuntu with GNOME idled at 894 MiB used (873 to 903), with a 533 MiB session. gnome-shell was half of it at 268 MiB, since on Wayland the shell is also the compositor and display server. It also had the quickest boot, reaching a running shell 11.2 seconds after the kernel started.
The number that matters more is RAM left for apps: 2,504 MiB, the lowest of all seven. The ubuntu-desktop metapackage recommends kdump-tools, so a normal install pulls it in, and it adds a crashkernel reservation to the kernel command line. The boot log shows the memory taken before anything else runs (the kernel kdump docs explain the range syntax):
[ 0.010194] crashkernel reserved: 0x000000009f000000 - 0x00000000bf000000 (512 MB)So the VM saw a MemTotal of 3,398 MiB instead of 3,910 MiB. Ubuntu’s default line reserves nothing under 2 GB of RAM, 320 MB from 2 to 4 GB, 512 MB from 4 to 32 GB, 1 GB from 32 to 64 GB, 2 GB from 64 to 128 GB and 4 GB above that. Most 4 GB machines land in the 512 MB tier, as our VM did, because the kernel rounds RAM up to the next 128 MB before matching and the top of each range is exclusive. None of the other flavours reserved crash kernel memory: all of them saw the full 3,910 MiB. If you don’t plan to collect kernel crash dumps, remove it. Purging the package alone is not enough, because the generated GRUB config keeps the old command line until you rebuild it:
sudo apt-get purge -y kdump-tools
sudo update-grub
sudo rebootAfter the reboot, free -m on the same VM showed a total of 3,910 MiB again, matching the other flavours. The ubuntu-desktop metapackage stays installed. We covered the same reservation in our Ubuntu vs Linux Mint test, and the rest of the release’s defaults are in the Ubuntu 26.04 features rundown.
Where it falls short: extensions and the Ubuntu Dock live inside gnome-shell, so every extension you add grows the one process that can’t be restarted on Wayland without logging out. The tested release was GNOME 50.
6. Cinnamon (Ubuntu Cinnamon)
Cinnamon idled at 960 MiB used (937 to 969) with a 578 MiB session. The cinnamon process (panel, window manager and compositor in one) was 137 MiB. The rest is a long tail of small settings daemons: csd-color, csd-wacom, csd-keyboard and csd-automount at 18 to 19 MiB each, plus nemo-desktop, IBus and Evolution’s calendar services.
Ubuntu Cinnamon was the smallest install on disk by far, largely because it installs no snaps (every other flavour had 7 or 8), adding only 2,950 MB (and 1,115 packages, second only to GNOME’s 1,006). The default session is X11; a cinnamon-wayland session is installed alongside it but is not the default. The tested build was Cinnamon 6.4.13.
The downside: it costs about 70 MiB more than GNOME at idle, and Ubuntu’s 6.4 build trails upstream’s stable 6.6 series. If you like Cinnamon but want Debian underneath, our Cinnamon on Debian guide covers it.
7. KDE Plasma (Kubuntu)
KDE Plasma was the heaviest at 1,209 MiB used (1,173 to 1,232), 782 MiB above the bare system. The session held 691 MiB, led by plasmashell at 291 MiB and the kwin_wayland compositor at 108 MiB. The kded6 module host adds 58 MiB, and Kubuntu also starts services you may not use: KDE Connect (45 MiB), the Discover update notifier (42 MiB) and the KDE Wallet secret service (41 MiB). On the root side, fwupd and PackageKit added another 49 MiB.
It was also the biggest install: 5,462 MB of disk and 1,640 packages. The tested build was Plasma 6.6.6 on Wayland with SDDM. It did not boot slowly, though: 12.7 seconds from kernel to panel, the same as LXQt.
The only real cost is memory, and some of it is optional. KDE Connect and the Discover notifier alone hold 87 MiB, and both can be switched off in System Settings if you do not use them. On any machine with 8 GB or more, the extra few hundred MiB buy the most configurable desktop of the seven. Our KDE Plasma on Debian guide covers the Debian route.
Check desktop RAM usage on your own machine
Log in, wait five minutes so startup jobs finish, and read free:
free -mOn the Xubuntu VM the “used” column read 901 MiB, inside the benchmark range of 867 to 942 MiB, and “available” is the memory your applications can actually get:
total used free shared buff/cache available
Mem: 3910 901 2206 13 1039 3009
Swap: 0 0 0Look at “total” too. On our 4,096 MB VMs it read 3,910 MiB on every flavour except stock Ubuntu, which read 3,398 MiB. A gap that size is the kdump reservation described above. Apart from Xorg, snap’s daemon was the largest system process on every flavour (35 to 44 MiB, even on the headless control), so the snap versus Flatpak trade-offs matter more to a small machine than the choice between two light desktops.
Also considered
- Ubuntu Unity: it has a 26.04 image, but no 26.04.1 point release, while every other flavour here has one.
- Ubuntu Kylin (UKUI): an official flavour, but it’s built and localised for Chinese-language users.
- Edubuntu and Ubuntu Studio: GNOME and KDE Plasma with large application bundles, so they measure the apps rather than the desktop.
Which desktop to pick for your RAM budget
| Your machine | Pick | Why |
|---|---|---|
| 4 GB or less | LXQt (Lubuntu) | Leaves 3,165 MiB free at idle, the most of the seven |
| 4 GB, want Wayland | Budgie | Second lowest at 806 MiB and the lightest Wayland desktop tested |
| 4 to 8 GB, classic layout | MATE or Xfce | 835 and 888 MiB; Xfce gets lighter once IBus and Evolution’s alarm notifier are removed |
| 8 GB and up, want stock Ubuntu | GNOME | Fastest from kernel to panel at 11.2 s; purge kdump-tools to get 512 MiB back |
| 8 GB and up, want control | KDE Plasma | Heaviest at 1,209 MiB, only 315 MiB above GNOME, and it buys the most features |
| Coming from Linux Mint | Cinnamon | Familiar layout at 960 MiB and the smallest install on disk |
For most people with 8 GB or more, the spread between these desktops matters less than one browser tab, so pick the one you like using. The ranking starts to matter at 4 GB, and there the order is clear: LXQt, then Budgie, then MATE.
It would be interesting to also test Phosh and Plasma Mobile, to see how they compare.
Good idea for a follow-up. This round only covered the seven desktops Ubuntu 26.04 ships as official flavours, and neither Phosh nor Plasma Mobile is one, so they’d need their own run, ideally on touch hardware since both are built for phones.