While Ubuntu 12.04 already did a very good job at enhancing the ARM performance, Ubuntu 12.10 already has a number of performance improvements for ARM devices. With Ubuntu 12.04 for ARM there were performance improvements thanks to switching to ARM hardfp binaries by default rather than the soft floating-point version.
The switch to the hardware floating-point build made a noticeable difference and for some hardware there were performance improvements due to upstream kernel improvements. With the Linux kernel found in 12.04 (Linux 3.2), there is proper support for the OMAP4460 as found in the PandaBoard ES. With that, the dual-core Cortex-A9 can now properly clock up to its rated 1.2GHz speed. Those reasons represent a bulk of the improvements for the ARM architecture in Ubuntu 12.04.
Ubuntu 12.10 has been in development for just over one month now, but I am already curious about the ARM performance for this next Ubuntu Linux release due out in October. There is going to be some exciting ARM tests coming on Phoronix so I was curious to see how Ubuntu 12.10 is shaping up. The main differences in Ubuntu 12.10 for potentially affecting the performance is the Linux 3.4 kernel (rather than 3.2) and moving to GCC 4.7 (instead of GCC 4.6 in 12.04 LTS).