KDE Plasma 6.7 To Provide A Much Better Experience For CPU-Based Rendering

KDE Plasma 6.7 will significantly improve CPU-based rendering performance in KWin by using Linux's UDMABUF to wrap MEMFD-allocated memory into DMA-BUF objects, eliminating costly texture upload copies to the GPU. Previously, Wayland shared memory (wl_shm) buffers required excess copies before reaching the GPU, causing KWin's main thread to block and spike CPU usage. With the fix, KWin will attempt to create a UDMABUF for each wl_shm buffer and import it directly into the GPU driver. Real-world results on a Ryzen 7840U show KWin CPU usage during scrolling dropped from 80-90% on one core to just 20%, with cursor smoothness fully restored. The improvement will ship in Plasma 6.7 and Qt 6.11.2.