Firefox 140 ESR Released: Key Features, Performance Boosts & Developer Updates

Discover Firefox 140 ESR’s latest features, including Unload Tabs, CSS Custom Highlighting API, Vertical Tabs, and Full-Page Translations. Learn how this update improves performance, memory efficiency, and developer tools. Download now!

Firefox 140 ESR: A Major Update for Performance & Customization

Mozilla has officially launched Firefox 140, marking its next Extended Support Release (ESR)—a version designed for long-term stability and enterprise use. 

This update introduces critical performance enhancements, new CSS styling capabilities, and improved tab management, making it a must-upgrade for power users and developers alike.

Key Features in Firefox 140 ESR

1. Unload Tabs for Better Performance

• Right-click any tab to "Unload Tab", freeing up memory and CPU resources.

• Ideal for users with multiple open tabs, reducing system strain without losing session data.

2. CSS Custom Highlighting API Support

• Now supports ::grammar-error and ::spelling-error pseudo-elements, allowing custom styling for text errors.

• Catches up with Google Chrome (since v121), offering better web compatibility.

3. Vertical Tabs & Custom Search Engines

• Improved Vertical Tabs for streamlined browsing.

• Users can now add custom search engines directly from the address bar.

4. Full-Page Translations with Smart Prioritization

• Firefox now prioritizes translating content near your view, improving speed and usability.

5. Developer-Focused Enhancements

• SVG fetchpriority attribute for optimized resource loading.

• Cookie Store API for better cookie management in web apps.

• Experimental features in Nightly builds:

  • Prioritized Task Scheduling API

  • Atomics.waitAsync for advanced JavaScript concurrency.

🔗 Full developer documentation: developer.mozilla.org

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Why Upgrade to Firefox 140 ESR?

• Lower memory usage with Unload Tabs.

• Better customization with CSS API and Vertical Tabs.

• Enhanced privacy & security (ESR versions receive extended security updates).

• Optimized for enterprise & power users needing long-term stability.

Download Firefox 140 ESR Now

📥 Official Download: Mozilla.org

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Frequently Asked Questions (FAQ)

❓ Is Firefox 140 ESR faster than previous versions?

✅ Yes—Unload Tabs and optimized translations reduce memory usage significantly.

❓ Does Firefox 140 support Chrome extensions?

⚠️ No, but Mozilla’s WebExtensions API ensures many popular add-ons are available.

❓ How long will Firefox 140 ESR receive updates?

📅 Typically 12 months, making it ideal for businesses and institutions.

 

Final Thoughts

Firefox 140 ESR delivers meaningful performance and customization upgrades, making it a strong choice for developers, enterprises, and privacy-focused users. With extended support and new APIs, it’s a competitive alternative to Chrome—especially for those valuing resource efficiency.

📌 Ready to upgrade? Get Firefox 140 ESR now!