We tested all the Ubuntu remixes for resource usage so you don't have to

Which flavors are the lightest and the heaviest disk and memory-wise?

The Reg FOSS desk has lined up the official Ubuntu remixes to see which ones hog the most or least of your computer's resources.

Whenever Linux users get together, an eternally popular subject for advocacy (which is the polite word for arguments) is desktops. Here at The Reg FOSS desk, we're as complicit as anyone. But oddly enough, the one aspect of desktop comparisons that is amenable to direct measurement rarely gets much attention: resource usage.

Resource usage is somewhat important. In direct terms, the less RAM and disk space your desktop uses, the more you have free for your own stuff. Secondly, desktops which are more frugal in resource usage are generally quicker and more responsive. That in turn means they run better on older, lower-spec computers. That's highly relevant because a popular use case for Linux is reviving an old PC whose copy of Windows is too outdated and sluggish to be useful any more.

In more theoretical terms, one could also say that the larger the resource footprint, the bigger the attack surface. More running code equals more opportunities for stuff to go wrong.

Under "flavors" on the Ubuntu desktop page, Canonical lists six alternate editions: Kubuntu, Lubuntu, Ubuntu Budgie, Ubuntu MATE, Ubuntu Studio, and Xubuntu. Since Ubuntu Studio uses the same KDE desktop as Kubuntu, we're skipping it: its main difference is in the pre-installed apps, and it's the desktops we're primarily interested in here.

In a day or so, we plan to return to this theme and take a look at some of the main unofficial flavors.

That still leaves six official editions – in Ubuntu's own order:

  1. Ubuntu, with GNOME 42;
  2. Kubuntu, with KDE 5.24.4;
  3. Lubuntu, with LXQt 0.17;
  4. Ubuntu Budgie, with Budgie 10.6.1;
  5. Ubuntu MATE, with MATE 1.26;
  6. Xubuntu, with Xfce 4.16.

Since 22.04.1 is now out, it seems fair to call the current LTS stable. The last time we compared the flavors was nearly a decade ago, and much has changed – including the lineup.

The contenders

Ubuntu

Ubuntu's installation process is usually smooth, and that hasn't changed. We've discussed the pros and cons of Ubuntu when we looked at the beta of this version, and the final released version. If you like GNOME, it's good. If you don't, well, that's why there are all these remixes.

We didn't install any extras. It automatically prompted for a few updates, and after that, apt didn't find any more. It geo-located the test machine to Prague, which is correct, and installed Czech localization, which isn't – we picked English as the system language. We left that as-is, for a fair comparison.

The login screen gives a choice of Wayland or X.org, and defaults to Wayland. We chose X.org, so as to be the same as the other flavors.

The default Ubuntu is the GNOME version, with Ubuntu's modest customizations to the desktop, such as a dock.

The default Ubuntu is the GNOME version, with Ubuntu's modest customizations to the desktop, such as a dock


Kubuntu

Kubuntu also installed smoothly, although with one niggle. Like the GNOME edition, it doesn't notice that it's in a VM and sets the screen to 800x600 – but that isn't enough to run the installation program. We had to reboot, pick "Try Kubuntu", load the full desktop and change the screen resolution to 1024x768, then we could complete the installation.

After installation, Kubuntu noticed some updates and prompted us, but then the apt full-upgrade command found a few more. After we installed those and rebooted, it then notified us that the localizations weren't fully installed.

Kubuntu, the oldest remix, appropriately has the current LTS KDE Plasma desktop

Kubuntu, the oldest remix, appropriately has the current LTS KDE Plasma desktop


Lubuntu

Lubuntu has always been the lightweight flavor of Ubuntu for older computers. Unfortunately, the parent distro has dropped support for 32-bit x86 so Lubuntu is now 64-bit only. That means it won't run on things like old Atom-based netbooks or other 32-bit machines.

To be fair, most 32-bit PCs are largely obsolete now. The snag is that some early 64-bit machines can take more RAM, but it's prohibitively expensive because they need DDR or DDR2, which simply didn't come in larger sizes.

Whatever the reason, if you're stuck with just two or three gigs of RAM, a 32-bit distro would be more memory efficient, but Lubuntu no longer has the option. If that's your situation, we suggest either the Raspberry Pi Desktop for low-end hardware or for well-specced kit the Debian edition of Linux Mint.

There's no "try or install" choice with Lubuntu. You boot straight to the desktop, with a link to the cross-platform Calamares installer. That's no bad thing: we were pleased to note that when we selected "English (UK)" as our language, that changed the locale and keyboard layout too. We ended up with an old-school username of "liamp". We also found that the login screen was set to US English, while the desktop was set to UK: not ideal, but not a problem either, and it's good to see it clearly highlighted.

The installer ran fine at 800x600, worked without any issues, and helpfully informed us that the default was to use a swap file. Neither boot disk nor installed system noticed it was in a VM, but neither captured the mouse either. The installed OS didn't prompt us for any updates, but it did tell us we were running the power-management tool for the first time, and showed a battery meter, neither of which is helpful in a VM. However, under Preferences, the launcher menu has a "apply full upgrade" entry. That seemed to do a very thorough job, complete with a new kernel version, and it took many minutes to complete. Afterwards, apt found no new updates.

You can't change the screen resolution by right-clicking the desktop, but that's common these days. Less so is that you can't do it by searching the launcher menu for "screen" or "display" either. "Monitor" is the keyword to look for. Also note that your changes won't be remembered unless you click "Save".

Lubuntu has a rather old version of LXQt, but it's small and it works

Lubuntu has a rather old version of LXQt, but it's small and it works


Ubuntu Budgie

The Budgie desktop from Solus OS is the newest desktop of this lineup, and it's probably the shiniest of the lot. It's refreshing to see something that isn't just another re-implementation of the classic Windows desktop. Like several other flavors, Budgie defaulted to 800x600, and the Ubiquity installer won't fit. But there was an extra annoying wrinkle: once we rebooted the VM, picked "Try Ubuntu Budgie", loaded the full desktop, changed the screen mode, and restarted the installation… halfway through it reset the screen mode back to 800x600 again so we couldn't reach the "Next" button.

Once installed, we changed the resolution again… but the panel didn't correctly resize, or the dock reposition itself, until we logged out and back in. That's surprising in 2022. We also got no notifications of any pending updates, although apt found 15.

Interestingly, Ubuntu Budgie claimed to be using the correct VirtualBox virtual display driver for the desktop, although the screen didn't resize with the VM's window, and some animation effects were a little juddery.

Ubuntu Budgie is shiny and colorful, albeit not particularly svelte

Ubuntu Budgie is shiny and colorful, albeit not particularly svelte


Ubuntu MATE

MATE started out as a fork of GNOME 2, and Ubuntu MATE feels very much like the classic Ubuntu from the Noughties, before Unity or GNOME 3. It even has the classic African-drums sound effects, and uses a green-tinted version of the parent distro's jellyfish wallpaper.

Almost the only visible difference from Ubuntu 10.10 or so is the default theme, which is flat and green-hued, rather than faux-3D-shaded brown or purple. It also collapses classic GNOME's three desktop menus (Applications, Places and System) down into one, called just "Menu".

As soon as the new OS booted, it prompted us to install updates. This was quick and thorough, leaving nothing for apt to do – although there was a snap update pending. We did experience a crash of the menu application, though, which is a little worrying.

Ubuntu MATE is cool, refreshing, and fairly lightweight, just like the distro used to be

Ubuntu MATE is cool, refreshing, and fairly lightweight, just like the distro used to be

Xubuntu

Xubuntu first appeared in 2006, a year after Kubuntu, making it the second oldest remix there is, and probably the one with the oldest desktop environment: Xfce even predates KDE, although Xfce wasn't open source until version 3.0 in 1999, when it switched from XForms to GTK+.

Post-install, it immediately prompted for updates, which is good – but the apt command found three more, plus the usual Snap updates.

Xubuntu omits the second panel that most Xfce distros provide, configured like a dock at bottom center. The result is a very minimal desktop, with no app-launcher icons, and not even a title for the launcher menu – perhaps a bit too minimal.

Given that Xfce excels at vertical taskbars, better than any other contemporary Windows-like desktop, we'd like to see it do that by default.

Xubuntu is light on RAM but includes all the apps and customization you could want

Xubuntu is light on RAM but includes all the apps and customization you could want


The numbers

  Disk used (GiB) Disk free (GiB) Usage (%) RAM used (MiB) RAM free (GiB) RAM shared (MiB) Buff/cache (MiB) Avail (GiB) ISO size (GiB)
Ubuntu 9.3 5.1 65 710 2.3 1 762 2.8 3.6
Kubuntu 11 4.2 72 584 2.6 11 556 2.9 3.5
Lubuntu 7.3 2.8 50 357 2.8 7 600 3.2 2.5
Ubuntu Budgie 9.8 4.6 69 657 2.4 5 719 2.9 2.4
Ubuntu MATE 10 4.4 70 591 2.5 9 714 2.9 2.5
Xubuntu 9.4 5 66 479 2.7 1 545 3.1 2.3


Rounding up and down

Most of the Ubuntu flavors use Canonical's own installer, Ubiquity. If you give it a two-word name, it uses the first word in lower case as the user account name: for example, liam. It also creates a 1.7GB swap file on the root partition, and sets the system locale to wherever your IP address is. If that's not right, you have to fix it yourself.

In contrast, Lubuntu uses the cross-platform Calamares installer instead. This creates a user account with the first name plus the initial of the last name: liamp. Lubuntu also uses a smaller, half-gigabyte swap file, so its disk score looks better than it really is. Even with an extra 1.2GB of swap to match the rest, it would still be the lightest by half a gig, though.

None of the remixes reported that they were running in a VM, which some distros – such as Deepin – do. Others, such as all the Mandriva variants, not only detect that they're running under a hypervisor but go a very helpful step further, automatically enabling the guest drivers, so that the virtual screen resizes with its window and enabling the hypervisor to accelerate the display. Ubuntu really ought to do the same.

All of them set the default screen resolution to 800x600, which is often too small to use the installation program: its window is too big to fit, and the buttons are invisible, off the edge of the screen. If necessary, we reset this to 1024x768 to complete the installation. None of them remembered this in the installed system. Worse still, both the Budgie and MATE remixes annoyingly reset the screen back to 800×600 again during the installation process.

Only the GNOME version offered the choice of Wayland or X.org.

Conclusions

All the remixes use less memory than the default GNOME edition. To be honest, we didn't expect that. The last time we did this comparison, in 2013, Kubuntu scoffed the most RAM – and as before, it still uses the most disk. KDE Plasma 5 really has slimmed down its memory footprint impressively, although it's still no lightweight.

The KDE, MATE, and Budgie editions are quite close in resource usage so in those terms, there's not a lot to choose between them. That means it's down to your personal preferences.

All credit to the Lubuntu team: their remix remains the lightest by quite some margin, both in memory and disk usage. Saying that, it does use an old version of the LXQt desktop. There is a repository to install a newer version, but that's a big ask for a non-techie user.

Xubuntu is the next lightest in RAM usage, although it uses more disk than the default GNOME edition – but then it does bundle apps like email, optical-disk burners and so on.

A nice touch is that both MATE and Budgie have friendly welcome screens. Budgie is probably the the most colorful remix, while for us, the MATE edition is cleanest-looking of the lot. Apps have classic menu bars, it has a unified Control Center for system settings, and it even uses similar wallpapers. Of all the remixes, MATE is the one that's most like the Ubuntu of old.

How we tested

We tested all the distros in identical VirtualBox VMs. The spec was 4,000MB of RAM, two CPU cores, a 16GB virtual hard disk, and VirtualBox's default graphics adapter with 3D acceleration enabled. Each machine was booted from the default ISO file downloaded from the project website, and as far as possible, we left settings on defaults.

If there was a choice, we did the "full" install of each distro, ticking both the options for installing updates, as well as for optional drivers and codecs. After that, we rebooted and gave each distro a few minutes to prompt for any updates. Whether it did or not, we then did a manual full update, like so:

sudo -s
apt update ; apt full-upgrade -y ; apt autoremove -y ; apt purge ; apt clean ; snap refresh

Those were installed, then it was rebooted again and left for a few minutes to settle. Disk usage was measured with df -h, and memory usage with watch free -h and then waiting for the numbers to stabilize.

The built-in Ubuntu Software Sources app did detect that the OS was running under a hypervisor, and offered to install the guest additions – but only if we ran it. No flavor prompted us to do this, but we feel it should.

We chose not to, and here's why. On bare metal, you wouldn't need it, and it requires installing DKMS, the core development tools, and the kernel headers, which considerably increases the disk footprint, whereas we wanted the unvarnished default numbers. ®

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