With the PostMark disk benchmark as the first test profile in use for this three-way Ubuntu Linux comparison, the mail server benchmark unfortunately sees degraded performance with each succeeding Ubuntu release. At this point in Ubuntu 13.04 development, PostMark is running at 85% the speed it was one year ago in Ubuntu 12.04.
For the NAS Parallel Benchmarks courtesy of NASA, there are no shocking changes in performance. Ubuntu 13.04 is still using GCC 4.7.2 like in Ubuntu 12.10. Ubuntu 12.04.1 LTS is using GCC 4.6, but there aren't many exciting performance optimizations (nor regressions) between GCC 4.6 and 4.7 for this aging Intel Atom processor.
There are a few possible performance slowdowns in some of the computational test cases, but nothing dramatic.