Experiments Are Underway With Vulkan Powering The KDE Plasma Shell
Given that Qt 5.15 has a tech preview of the new Render Hardware Interface (RHI) with Vulkan support for Qt Quick, Edmundson was experimenting with getting Vulkan rendering the Plasma shell. With a few Plasma changes, the necessary development packages for Vulkan, and some tweaks to the environment variables, he was able to get a working Vulkan-powered Plasma shell.
Edmundson noted of the KDE Plasma shell Vulkan experience, "Despite it being a preview it is in a damn good state! Things are usable, and really quite snappy, especially notification popups."
But there still is more work to do like porting their custom shaders, untieing some areas that use low-level OpenGL code, making use of Qt Quick widgets for system settings, and other areas. This is also an effort only about the shell and not about the KWin compositor, which is still using OpenGL. There was some work in the past on getting KWin to use Vulkan but nothing current at the moment it seems.
The longtime KDE developer concluded in his blog that this Vulkan support for the Plasma shell is unlikely to ever be officially supported with Plasma 5. This prep work, however, is promising and likely will be delivering a native Vulkan experience with KDE Plasma 6.