The Silent Mouse
Power management in Linux is often highly aggressive by default to maximize laptop battery life. One of the consequences of this behavior in Ubuntu is the USB auto-suspend feature, which often extends to the internal Bluetooth controller. If you are using a Bluetooth mouse or keyboard and leave it idle for just a few minutes while reading an article, Ubuntu may automatically suspend power to the Bluetooth radio. When you move your mouse again, there is a noticeable 2-to-3-second delay while the hardware wakes up and reconnects, leading to a stuttering, frustrating user experience.
Disabling Bluetooth Power Management
To ensure an instant response from your wireless peripherals and stop Ubuntu from automatically suspending your Bluetooth hardware to save power, you must explicitly disable the USB auto-suspend feature for the Bluetooth module.
Open your terminal (Ctrl+Alt+T). You need to modify the GRUB bootloader configuration to pass a kernel parameter that disables this behavior globally. Type: sudo nano /etc/default/grub and press Enter. Look for the line that begins with GRUB_CMDLINE_LINUX_DEFAULT=. It likely currently says something like "quiet splash". You need to add the parameter to disable USB auto-suspend. Modify the line so it looks exactly like this: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash usbcore.autosuspend=-1". Press Ctrl+O, then Enter to save the file, and Ctrl+X to exit the Nano editor. Finally, you must update the bootloader for the changes to take effect by typing: sudo update-grub. Restart your computer. Your Bluetooth adapter will now remain fully powered at all times, eliminating the annoying wake-up lag.