Faster Chromium - Speed Up Any Website

A Chrome/Edge Extension (Manifest V3) that improves website performance through smart resource loading, rendering optimizations, and runtime tuning. Written in vanilla JavaScript with no build tools or dependencies.

Does not block ads or trackers -- designed to run alongside uBlock Origin without conflicts.

Installation

1. Open chrome://extensions/ (or edge://extensions/)
2. Enable Developer mode
3. Click Load unpacked and select this folder

After code changes, click the reload button on the extension card. For content script changes, also reload the target page.

Features

Resource Loading

Feature	Default	Description
DNS Prefetch	ON	Injects dns-prefetch and preconnect hints for third-party domains (max 10)
Preload Hero Image	ON	Detects and preloads the largest visible image (LCP candidate)
Image Priority	ON	Sets fetchpriority high/low based on viewport position and decoding="async"
Lazy Load Images	ON	Adds loading="lazy" to images missing the attribute
Lazy Load Iframes	ON	Adds loading="lazy" to iframes (YouTube embeds, maps, social widgets)
Reduce Media Preload	ON	Downgrades preload="auto" to preload="metadata" on video/audio elements
Prefetch Links	OFF	Prefetches same-origin visible links during idle time (max 5, uses bandwidth)

Rendering

Feature	Default	Description
Disable Animations	ON	Suppresses CSS animations, transitions, and smooth scroll
Stop Autoplay	ON	Pauses video/audio autoplay elements
Font Display Swap	ON	Sets font-display: swap on same-origin @font-face rules to prevent invisible text flash
Non-Blocking CSS	ON	Makes render-blocking stylesheets non-blocking via media="print" + onload pattern
Content Visibility	ON	Applies content-visibility: auto to off-screen sections for skip rendering
Stabilize Layout	ON	Sets explicit width/height on images to reduce Cumulative Layout Shift (CLS)

Scripts & Interaction

Feature	Default	Description
Throttle Timers	ON	Enforces minimum delays on setInterval (100ms) and setTimeout (10ms)
Passive Listeners	ON	Forces passive: true on scroll/touch event listeners for smoother scrolling
Defer Scripts	OFF	Replaces synchronous scripts with deferred versions (experimental, can break pages)

Architecture

The extension operates across four layers:

Layer 1: Settings -- background.js (Service Worker)

Manages settings in chrome.storage.sync under the key fasterChromiumSettings. Acts as the central message hub between popup and content scripts. Handles settings migration from v1.x on extension update.

Layer 2: DOM -- content.js (Content Script)

Injected at document_start on all pages. Applies performance optimizations across three phases:

• document_start: Injects injected.js into page context, disables CSS animations, sets up MutationObserver
• DOMContentLoaded: Lazy loading (images + iframes), autoplay prevention, media preload reduction, image optimization (priority/decoding), DNS prefetch/preconnect, LCP preload, font-display swap, non-blocking CSS, content-visibility, layout stabilization
• load: Second-pass layout stabilization, link prefetching via IntersectionObserver, load time capture

Uses a debounced requestIdleCallback scheduler to apply optimizations to dynamically added elements. The MutationObserver also intercepts new <link rel="stylesheet"> elements to apply the non-blocking CSS pattern before they block rendering.

Layer 3: Runtime -- injected.js (Page Context)

Injected into the actual page context (not the isolated content script world) via a <script> tag. This is necessary because code running in the page context operates under the page's CSP, not the extension's CSP. Contains:

• Timer throttling: Monkey-patches setInterval/setTimeout to enforce minimum delays
• Passive event listeners: Patches EventTarget.prototype.addEventListener to force passive on scroll/touch events
• Script deferral: MutationObserver that intercepts synchronous same-origin scripts and replaces them with deferred versions

Layer 4: UI -- popup.html + popup.js

Settings interface with master toggle, per-feature toggles organized in three sections, live stats (active features, images optimized, estimated time saved), and refresh/reset actions. Dark theme with green (#22c55e) accent.

Message Protocol

Components communicate via chrome.runtime.sendMessage / chrome.tabs.sendMessage:

Message Type	Direction	Purpose
GET_SETTINGS	Popup/Content -> Background	Retrieve current settings
SAVE_SETTINGS	Popup -> Background	Persist settings
SETTINGS_UPDATED	Background -> All tabs	Broadcast after settings change
GET_METRICS	Popup -> Content	Get performance metrics for active tab
TOGGLE_ENABLED	Any -> Background	Toggle master switch
REFRESH_OPTIMIZATIONS	Popup -> Content	Reapply all optimizations

Popup Stats

The popup displays three metrics for the active tab:

• Active: Number of enabled feature toggles
• Images: Count of images optimized (priority + decode attributes set)
• Est. Saved: Estimated time saved based on concrete optimizations applied (per-item estimates: images 15ms, iframes 150ms, media 100ms, CSS 80ms, DNS 40ms, links 200ms, animations 30ms)

Conventions

• Each script file uses an IIFE wrapper for namespace isolation
• 'use strict' throughout
• Async/await for storage operations
• Silent error handling (.catch(() => {})) on cross-tab messaging since tabs may not have listeners
• requestIdleCallback with debounced scheduling for deferred cleanup work
• Data attributes track processed elements to avoid duplicate work:
  • data-fc-optimized -- image priority/decoding applied
  • data-fc-stabilized -- explicit dimensions set
  • data-fc-cv -- content-visibility applied
  • data-fc-media-opt -- media preload reduced
  • data-fc-nb -- non-blocking CSS applied
• Style IDs for injected CSS to enable clean removal:
  • faster-chromium-disable-animations
  • faster-chromium-content-visibility

Privacy

• No data collection or telemetry
• No external requests from the extension itself
• Settings stored in Chrome's sync storage only
• All code is visible and auditable

License

MIT License - Free to use, modify, and distribute.