Ubuntu With Linux 3.16 Smashes OS X 10.9.4 On The MacBook Air
The Intel Haswell OpenGL driver on OS X was formerly faster than the Intel Linux driver, but these days the open-source driver with the latest Intel DRM driver in the Linux kernel and user-space Intel Mesa OpenGL driver are faster for many workloads.
For some computational tests the Core i5 MacBook Air was running quite slow -- slower than OS X -- while it was much faster with the Linux 3.16 kernel. The CPU performance differences might come down to Ubuntu 14.04's 3.13 kernel defaulting to the ACPI CPUfreq driver with ondemand governor while the Linux 3.16 kernel from the Ubuntu Mainline Kernel PPA configuration defaults to Intel P-State with the performance governor.