On my older XPS 15 laptop, plugging into an external display defaults to the integrated GPU—and the result is constant input lag. Even with low CPU/GPU usage, the system feels unresponsive.

Source from: https://darkghosthunter.medium.com/bluefin-making-your-nvidia-dgpu-primary-for-external-monitors-0b5a293a4b9f

Problem

When you plug your laptop into an external display, GNOME/Mutter defaults to the integrated GPU. Even though your discrete NVIDIA GPU sits idle and CPU usage is low, the desktop feels sluggish: mouse clicks lag, windows stutter, and dragging feels delayed.

TL;DR

Force Mutter to use the NVIDIA dGPU for all external monitors by adding a udev rule.

Prerequisites

• A Linux distro running GNOME 43+ (with Mutter).
• Root (sudo) access.
• lspci installed.

Find Your NVIDIA IDs

Run:

lspci -nn | grep -i nvidia

Note the two hexadecimal codes in brackets:

01:00.0 3D controller [0302]: NVIDIA Corporation Device [10de:1c82] (rev a1)

• Vendor ID: 10de
• Device ID: 1c82

Create the udev Rule

1. Open a new rule file:

sudo nano /etc/udev/rules.d/61-mutter-dgpu-preferred.rules

2. Paste, replacing VENDOR_ID and DEVICE_ID:

SUBSYSTEM=="drm", ENV{DEVTYPE}=="drm_minor", ENV{DEVNAME}=="/dev/dri/card[0-9]", SUBSYSTEMS=="pci", ATTRS{vendor}=="0xVENDOR_ID", ATTRS{device}=="0xDEVICE_ID", TAG+="mutter-device-preferred-primary"

Example:

SUBSYSTEM=="drm", ENV{DEVTYPE}=="drm_minor", ENV{DEVNAME}=="/dev/dri/card[0-9]", SUBSYSTEMS=="pci", ATTRS{vendor}=="0x10de", ATTRS{device}=="0x1c82", TAG+="mutter-device-preferred-primary"

Apply & Verify

Simply reboot to apply the rules

Result: External displays now render on your NVIDIA card, banishing input latency and restoring silky-smooth desktop performance.