Fulcrum — Scroll Speed Tuner by Amber

Scroll speed in Firefox is one setting for every website. Fulcrum makes it per-domain.

Slack fires three screens per wheel tick. Some documentation sites need you to flick the wheel a dozen times to move a paragraph. These sites need different speeds — and you shouldn't have to adjust a global setting every time you switch tabs.

Fulcrum intercepts scroll events, applies your per-site multiplier, and moves on. It remembers every site you've configured. Open a page you've visited before and your preferred scroll speed is already there.

HOW IT WORKS

→ Open the Fulcrum popup on any page
→ Drag the slider or use the ¼× · ½× · 1× · 1.5× · 2× · 3× preset buttons
→ Close the popup — the speed is saved for that domain immediately
→ Return to the page any time and your setting is applied automatically

The "Default speed" section sets the fallback for sites you haven't configured yet.

⚙️ WHAT YOU CAN ADJUST

• Per-site speed: 0.1× (very slow) to 5× (very fast), in precise increments
• Default speed for all unconfigured sites
• Quick presets for common values
• View and reset all saved speeds from one place
• Enable / disable without losing your settings

🔒 YOUR PRIVACY

Fulcrum only stores domain names and speed values, locally in your browser. It reads no page content, makes no network requests, and sends nothing anywhere. The scroll interception happens entirely in your browser.

Note: sites that implement fully custom scroll (virtual lists, infinite feeds) may not be affected by Fulcrum's multiplier, as their scroll logic bypasses the standard browser wheel event.