What's exciting about Gran Paradiso is its new rendering engine. The Gekko 1.9 rendering engine will introduce some changes. For example, Firefox 3 will no longer support Windows 95, 98, and Me, and for the Mac OS X, versions 10.2 and earlier will not longer be supported. There will also be numerous changes made to the Document Object Model (DOM) in Gekko 1.9, which will affect developers more than end users. Also, there will be changes in the way Firefox renders frames within its display and the way object tags are handled, as well as changes in event threading.
Also new are its advanced graphics rendering capabilities. Firefox 3 uses open-source vector graphics (code-named Cairo, and formerly known as Xr) to provide high-quality display and print rendering. Currently Cairo supports output produced by X Windows, OpenGL, Quartz, Win32, in-memory image buffers, PNG images, PostScript, and PDF files. Cairo attempts to reproduce identical images on all output media (paper, disc drives, and such) and use hardware acceleration where possible to improve images on display screens.
Mac OS X users will experience a more native look and feel, better platform integration, and performance as Firefox incorporates the latest Mac OS API's.