When running ETXReaL at 1920 x 1080, the HD 4000 graphics with the i7-3770K is about 18% faster than the HD 3000 graphics with the i5-2500K and 82% faster than the HD 2000 graphics with the i5-2400S. The fastest for ETXReaL, a game that vastly reworks the open-source id Tech 3 engine to empower Enemy Territory with a new level of visual fidelity, was the A8-3870K Radeon HD 6550D graphics that were three times as fast. However, the slowest competitor was the AMD A8-3870K with the open-source Radeon Gallium3D driver. Evidently, Llano on the open-source driver by default is having clocking issues. With that said, Ivy Bridge easily smashed those results.
While the Catalyst driver with the A8-3870K still came well in front, the Intel Core i7 3700K with its open-source Linux 3.4 / Mesa 8.1-devel configuration was 64% faster than the Sandy Bridge graphics on the Intel Core i5 2500K with the same software/hardware configuration. The i7-3770K was also 2.05x faster than the HD 2000 graphics found on the Core i5 2400S. Ivy Bridge is doing very well over Sandy Bridge with the latest open-source Linux driver code. It will be interesting to see how the Ivy Bridge HD 2500 graphics are once I get my hands on some of those processors.
When running Nexuiz at 1920 x 1080, the Ivy Bridge HD 4000 graphics were now nearly on par with the AMD A8-3870K Fusion when it was powered by the Catalyst binary driver! This is quite impressive with the Intel integrated graphics on the open-source driver now on-par with AMD's competition while backed by their highly-optimized but proprietary Catalyst driver. This GLSL-using open-source game was 73% faster than the Intel Core i5 2500K (HD 3000) graphics and 2.06x faster than the Intel Core i5 2400S (HD 2000) graphics.
With the older OpenArena 0.8.5 release, the Intel Core i7 3770K was still running at around the same speed as the A8-3870K Llano. The i7-3770K HD 4000 here was 59% faster than the HD 3000 and 93% faster than the HD 2000 graphics. There are slight clock differences between the processors, but not by such wide margins to account for the extreme performance boosts out of Ivy Bridge under Linux.