# Background Tab Throttling — Cut Chrome CPU at Rest (2026)

> Background tabs keep burning CPU even when hidden, heating your laptop and draining battery. This PRO toggle slows them so the tab you're using stays fast.

- Canonical: https://www.superchargebrowser.com/features/js-throttling/
- Extension: performance
- Published: 2026-05-12
- Updated: 2026-06-11
- Source: SuperchargeBrowser (https://www.superchargebrowser.com)

Background tabs don't stop working when you leave them. Scripts keep running — polling for data, ticking animation frames, executing recurring callbacks. Most of that activity is invisible to you but visible to your CPU.

## What Gets Throttled

When Throttle Background Activity is on, `setTimeout`, `setInterval`, and `requestAnimationFrame` callbacks get clamped to longer intervals. Background tabs (where `document.hidden` is `true`) get aggressive clamps: sub-100ms timers become 500ms, sub-1s become 2s, sub-5s become 5s, animation frames drop to roughly 10fps.

The active tab is not exempt. It gets a much lighter floor — sub-50ms timers clamp to 100ms, sub-500ms timers respect a 100ms minimum, and timers ≥500ms run untouched. The intent is to suppress micro-poll abuse from page scripts without affecting normal interactivity.

## Who This Is For

The feature is most useful on machines where Chrome's CPU usage stays high even when you're not actively loading pages. Open Chrome's Task Manager (`Shift+Esc`) and sort by CPU. If several background tabs are consistently showing nonzero CPU percentages, this toggle directly addresses that.

On machines with plenty of headroom, the difference may not be noticeable. On older hardware, constrained laptops, or sessions with 20+ tabs, reclaiming that background CPU can meaningfully improve responsiveness in your active tab.

## PRO-Only

Throttle Background Activity requires a PRO license. It appears in the popup under the Control category with a PRO badge when the free tier is active.

## Whitelist First

If you run a web app in a background tab that needs accurate timing — a dashboard, a communication tool, a live data view — add its domain to the whitelist before enabling this feature. Whitelisted domains are excluded from script throttling (and any other Perf feature you list in the whitelist entry). Tab suspension already protects 25+ web app domains automatically, but throttling does not — the whitelist is your only escape hatch.

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Canonical URL: https://www.superchargebrowser.com/features/js-throttling/