Buffer more video: media.cache_readhead_limit = lots

Disable backspace-to-go-back to prevent accidental form loss: browser.backspace_action = 0

Warning on Ctrl-Q: browser.tabs.warnOnClose = true browser.showQuitWarning = true and DO NOT SET “Show my windows and tabs from last time”! Also, a WebExtension for this.

Wide gamut color: gfx.color_management.mode = 1

Save session less often: browser.sessionstore.interval = 60000

Kill safe mode prompt: toolkit.startup.max_resumed_crashes = -1

Force compositing acceleration: layers.acceleration.force-enabled = true

Force canvas acceleration: gfx.canvas.azure.accelerated = true (must create)

Smooth libinput touchpad scrolling and touchscreen on X11 (not needed on Wayland): MOZ_USE_XINPUT2=1

Faster mouse scrolling: mousewheel.default.delta_multiplier_y = 150

Arch Wiki Firefox/Tweaks

How to stop Firefox from making automatic connections