KDE Plasma is a lot lighter on your system resource than it used to be. There are options out there that are even lighter. As of late, I have been acquainted with many light weight distributios, BunsenLabs, MX, antiX, PeppermintOS and more that are even lighter than a basic KDE Plasma. They are all fantastic distributions and have great implementations of XFCE, LXDE or mixtures of the two and use OpenBox or some other window manger. The default window manager in LXQt on openSUSE is OpenBox and it is a fine window manager but has a dated appearance to it and the beauty of Linux is to be able to mix and match components to your hearts content.
I like the features of Kwin, and the window decorations it brings along with some other usability features I have come to expect on my Desktop Environments. OpenBox is satisfactory and great for what it is but Kwin matches my preferences better.
These instructions are assuming you have installed openSUSE without KDE Plasma as the default desktop. If you have previously installed KDE Plasma and you are just switching the window manager, jump to the Switch Window Manager section.
sudo zypper install kwin5 oxygen5 systemsettings5
Since you are installing a bunch of the KDE Plasma components you are going to pull down all the related dependencies. The oxygen5 package is completely optional but since that is still my favorite Window Decoration, I have included it. Feel free to punch in your favorite dressing there or remove that flavor all together.
Switch Window Manager
After the necessary Plasma components are installed, the next step is to switch out OpenBox with Kwin
In the system menu select: Preferences > LXQt Settings > LXQt Configuration Center
Select Session Settings
In the LXQt Session Settings window, Select Basic Settings and under Window Manager, select Kwin_x11.
Select Close, log out and log back in for the changes to take affect.
Upon logging back in, you should immediately notice the system menu looks so much smoother. Should you decide to further tweak your window settings. That can be done under Preferences > KDE System Settings.
This will bring up the familiar and fantastic System Settings from the Plasma Desktop Environment. This will allow you to make further visually pleasing changes to your desktop.
KDE Plasma is by far my favorite desktop environment and it is pretty light weight (relatively speaking) these days under openSUSE. It will run pretty decent on older or limited hardware. However, when memory is limited, say, 1 or 2 GiB of RAM, an extra 100 or so MiB of RAM is kind of a big deal. LXQt is a real nice desktop environment and when compared to some of the other low resource desktops like XFCE, often doesn’t feel as mature, especially when compared to MX Linux or PeppermintOS. Making this little Window Manager switch makes, in my estimation, improves the user experience.
I run this setup on my netbooks and low end laptops. Kwin does use an addition 34 MiB of RAM as compared to OpenBox but I am willing to make that trade-off for the improved interface features. I think a larger smile when using my hardware is worth 34 MiB.