> though I'd be quite surprised if disabling the compositor resulted in less tearing
I have been running OpenGL based applications on KDE for some time and the answer to tearing was always disabling the compositor in the desktop settings or just overriding the compositor related redirect state of the window. OpenGL tends to sync against vblank anyway so I don't find it surprising that rendering directly to the final output buffer instead of an off screen buffer that is at the mercy of the compositor helps.
I have been running OpenGL based applications on KDE for some time and the answer to tearing was always disabling the compositor in the desktop settings or just overriding the compositor related redirect state of the window. OpenGL tends to sync against vblank anyway so I don't find it surprising that rendering directly to the final output buffer instead of an off screen buffer that is at the mercy of the compositor helps.