Proper and extensive benchmarks of Fedora 17 against Ubuntu 12.04 LTS are forthcoming, but here's a preview of some results.
Benchmarks of Fedora 17 versus Ubuntu 12.04 LTS are coming soon now that the "Beefy Miracle" has been officially released. (Development builds of Fedora aren't benchmarked since Red Hat's been sticking a bunch of debug stuff into their pre-final kernel and packages that can impact the performance compared to Ubuntu's always-standard state.) The results in full from multiple systems will be published by month's end, but here is just a preview when comparing the x86_64 versions of Fedora 17 and Ubuntu 12.04 LTS on a single system.
System details and the benchmark results in full are available via OpenBenchmarking.org. You can also compare your system's performance to these results with the Phoronix Test Suite by running phoronix-test-suite benchmark 1206074-SU-1206062SU09. Embedded below are just some of the most interesting results from this system with an Intel Core 2 Duo T9300 "Penryn" processor, NVIDIA Quadro NVS 140M graphics, 4GB of RAM, and a 100GB HDD. Both Fedora 17 and Ubuntu 12.04 were tested in their default states.
From the HDD-backed notebook, Fedora 17 tended to have better file-system performance than Ubuntu 12.04 LTS. Fedora 17 is using the Linux 3.3 kernel while Ubuntu 12.04 is on Linux 3.2. Both are using the EXT4 file-system at present, but with Fedora 18 is where the hat wearing crew might switch to Btrfs.
Fedora 17 also won a number of the computational benchmarks over Ubuntu 12.04 LTS on the dual-core Intel 64-bit processor, but Fedora 17 was quick to adopt GCC 4.7 where as Ubuntu 12.04 LTS took the conservative approach of living with GCC 4.6. GCC 4.7 benchmarks have indicated a number of performance improvements out of this major compiler update.