picom: Sample confing in gentoo with xfce4 and nouveau dirver

Picom on Nouveau: Which Backend to Use If you're running the open-source nouveau NVIDIA driver and using the picom compositor, you've likely run into rendering glitches or crashes. The culprit is almost always the backend. Picom's GLX backend relies heavily on OpenGL, and nouveau's OpenGL support is incomplete. Stick to the xrender backend instead — it's slower, but stable. Create a config file at

~/.config/picom/picom.conf

with the following content:
backend = "xrender";

Vsync — disable, nouveau's support is unreliable
vsync = false;

Shadows
shadow = true;
shadow-radius = 7;
shadow-opacity = 0.75;
shadow-offset-x = -7;
shadow-offset-y = -7;

Fading
fading = true;
fade-in-step = 0.03;
fade-out-step = 0.03;

Opacity
inactive-opacity = 1.0;
frame-opacity = 1.0;
Then restart picom: pkill picom; picom -b
That's it. You trade some visual effects (blur requires GLX) for a stable desktop. If you ever switch to the proprietary NVIDIA driver, revisit the GLX backend for better performance.