I am also experiencing the exact same issue on KDE Neon 5.10.4 and nvidia-384.59, and switching to Xrender also fixes it for me.
Note that for me turning off compositing while using OpenGL 3.1 had a salutory effect but did not completely resolve the problem. For example, chromium still showed the issue but Konsole, system settings, and nvidia-settings did not (I just had these up at the time).
I also noticed this issue crop up after updating to xorg 1.19.3. I initially thought it was due to me running the Ubuntu 4.11.4-lowlatency mainline kernel, but I also see the issue on 4.12.5.
I am also experiencing the exact same issue on KDE Neon 5.10.4 and nvidia-384.59, and switching to Xrender also fixes it for me.
Note that for me turning off compositing while using OpenGL 3.1 had a salutory effect but did not completely resolve the problem. For example, chromium still showed the issue but Konsole, system settings, and nvidia-settings did not (I just had these up at the time).
I also noticed this issue crop up after updating to xorg 1.19.3. I initially thought it was due to me running the Ubuntu 4.11.4-lowlatency mainline kernel, but I also see the issue on 4.12.5.