Firefox 4

Firefox 4  is based on the Gecko 2.0 Web platform.  This release incorporates new features, such as: increased performance while viewing Flash content, improved plug-in compatibility with hardware acceleration enabled, hovering over links now displays the URL at the bottom of the window rather than in the location bar, as well as general stability, performance, and compatibility improvements.

Additionally, this release includes features from previous Firefox 4 Beta versions, like: availability in 77 languages, support for the proposed Do Not Track header, connection status messages now shown in a small overlay, re-enabled WebGL on Linux, refreshed the default homepage design and speed, functionality, and compatibility improvements to WebGL.

Also, Firefox no longer switches into offline mode automatically, overhauls the bookmarks and history code, enabling faster bookmarking and startup performance and The Firefox Sync setup experience has been improved across desktop and mobile devices.

Moreover, Per-compartment garbage collection is now enabled, reducing work done during complex animations, and web typography is improved using OpenType with support for ligatures, kerning and font variants.