Chris Titus recently vlogged about an article showing that KDE 5.17 is now smaller than XFCE 4.14 in memory usage. The article says that in their tests, XFCE actually uses more RAM than KDE. I was very interested in this, but I couldn’t quite believe it and so I ran my own tests.

First of all, we need to compare apples to apples. I created an OpenSUSE VM using Vagrant with KVM/libvirt. It had 4 cores and 4192MB of RAM. This VM has no graphical interface at all. As soon as I got it up, I took the first “No X” measurement. After patching using zypper dup, I took the second “No X” reading. Every reading in this blog post was using the free -m command. I then shut down the VM and cloned it 3 times so each copy should be completely the same.

I installed the desktop environments into their respective VMs using the following commands:

zypper in -t pattern kde zypper in -t pattern xfce zypper in -t pattern gnome

After desktop environment was done, I then installed the lightdm display manager. This wasn’t actually necessary with Gnome because it installs gdm as a dependency.

After that, I started the display manager with:

systemctl set-default graphical && systemctl isolate graphical

Once I logging into the graphical environment, I ran xterm and then free -m for the first reading. I then rebooted each machine, and logged in for the second reading. I then installed and started libreoffice-writer. I created a new spreadsheet. That is the “Libreoffice” reading. Finally, I closed LibreOffice and took the third reading.

The results are a little surprising. The averages speak for themselves. KDE does use more than XFCE but not to a shocking amount. In fact, according to the average, only about 68MB. What’s really surprising is how much more Gnome uses than the either two — nearly 200MB more that KDE!

Finally, I also did a df -kh after installing libreoffice-writer on each. KDE is in fact that disk hog by a wide margin and that’s even comparing it to Gnome + gdm + lightdm.

Desktop Test No RAM (MB) Disk (GB) Version No X 1 54 No X 2 58 Average 56 Gnome 1 471 3.34.2 Gnome 2 501 Gnome 3 508 Gnome Libreoffice 547 1.9 Average 507 KDE 1 327 5.17.4 KDE 2 284 KDE 3 291 KDE Libreoffice 330 2.3 Average 308 XFCE 1 216 4.14 XFCE 2 230 XFCE 3 241 XFCE Libreoffice 272 1.8 Average 240