These times the Mozilla Foundation is working a Direct2D acceleration for their Browser. Especially users how tend to have loads of plugins installed and numerous tabs open will profit from these optimizations.
Right now the Direct2D support is in the Alpha stadium which means that it wont be ready until the release of Gecko 1.9.3. It looks like it might take a year from now until the acceleration goes final.
Also sofware giant Microsoft said that upcoming versions of its browser Internet Explorer will support acceleration by graphics cards.
Source: FudzillaTo the comments