As it's been some months since last running any Linux vs. Mac OS X performance benchmarks, up today are benchmarks of the latest OS X 10.9.4 release on a Haswell-based Apple MacBook Air compared to running Ubuntu 14.04 LTS on the same hardware with also upgrading against the Linux 3.16 development kernel.
The MacBook Air used for testing was with the Intel Core i5 4250U processor (dual-core plus Hyper Threading; 1.30GHz base frequency, 2.60GHz Turbo), Intel HD Graphics 5000 (Haswell-ULT), 4GB of DDR3 system memory, and a 120GB Apple SSD. OS X 10.9.4 was run with its default state and using their preferred Xcode development stack that provides LLVM 3.4 SVN.
Ubuntu 14.04 LTS x86_64 was then dual-booted to the same Apple MacBook Air. Ubuntu 14.04 LTS was run with the Xfce desktop environment and we also enabled the Oibaf PPA for obtaining Mesa 10.3-devel for the latest with Intel's Linux graphics driver code for the HD Graphics 5000. After doing the Ubuntu 14.04 LTS run with the stock kernel, I then upgraded to the Linux 3.16 development kernel on the same stack. No hardware changes were made during testing (the CPU frequency reporting differences and other information just comes down to hardware detection/reporting changes on the different kernels).
All of the OS X and Linux benchmarking was done via the open-source Phoronix Test Suite.