Firefox version is arguably controversial because of age Firefox 4 is so fast. Intense competition with Google Chrome Mozilla forced to do a lot of changes.
New on Mozilla Firefox 5
- Support CSS Animations
- Placement feature Do-Not-Track for easy access
- Increased idle HTTP connection logic to improve performance
- Improved canvas, JavaScript, memory, and network performance
- Increased support for the HTML5 standard, XHR, MathML, SMIL, and canvas
- Increased capabilities for multiple languages misspelled
- Improved desktop integration for Linux users
- WebGL no longer be able to load the texture cross-domain
- 1000ms setTimeout and setInterval to improve performance
- Fixes some stability issues
- Fixes several security issues