Intel Broadwell HD Graphics 5500: Windows 8.1 vs. Linux
The Unigine Tropics test showed that the Intel Linux driver still has a ways to go in catching up to Windows 8.1 with the OpenGL performance for the Broadwell HD Graphics 5500.
The last Unigine test to be run was the newest Valley demo and it pushes the Broadwell graphics hardware quite bad and the Windows 8.1 number came out ahead of all five tested Linux configurations.
Xonotic with high image quality settings was playable on the X1 Carbon with HD Graphics 5500 when running at 1080p. With the initial Ubuntu 14.10 configuration when using Utopic's Mesa 10.3 packages, the frame-rate was getting locked to 60 FPS even though the Phoronix Test Suite overrides the sync/vblank settings. However, when switching to Mesa 10.5 this was no longer an issue. With the most updated configuration (Linux 3.19/drm-intel-next + Mesa 10.5-devel), the Windows 8.1 configuration was still 17% faster than Linux.
Xonotic with ultra image quality settings at 1080p showed Windows 8.1 being faster by about 33% with the latest Intel Linux code not helping out the situation.
With Xonotic at its ultimate image quality level, Windows 8.1 remained faster by 33% while the newer Linux kernel and Mesa code hadn't improved the situation over stock Ubuntu 14.10.