Published today are benchmarks from two Intel systems comparing the performance of Fedora 19 "Schrödinger's Cat" to Fedora 20 "Heisenbug" for various workloads. Especially for those using open-source graphics drivers, Fedora 20 can be worth the upgrade for performance reasons.
The benchmarks today are comparing clean installations of Fedora 19 x86_64 to the near-final packages of Fedora 20 x86_64. The key information for those evaluating Fedora 20 for Linux performance reasons is that the new release has the Linux 3.11 kernel and (if open-source graphics drivers are important to you) Mesa 9.2.3. Fedora 19 had shipped with Linux 3.9 and Mesa 9.2.0-devel, but kernel upgrades to F19 are also available for bumping the system to Linux 3.11. Both Fedora 19 and 20 are using the GCC 4.8.2 compiler since GCC 4.9 isn't being released until sometime in H1'2014.
It's a bit unfortunate that Fedora 20 didn't opt for shipping Mesa 10.0 (or some -devel snapshot as is usually common). There's many improvements to find with Mesa 10.0. Fedora 20 is also shipping with X.Org Server 1.14.4 over some X.Org Server 1.15 snapshot ahead of its official release before the end of December. Finally yet importantly, Fedora 20 is not shipping with Linux 3.12 that's been stable for a while but it can be found as a stable release update.
For today's Fedora 19 vs. Fedora 20 benchmarking the performance was measured on a Lini PC with Intel Pentium G3220 dual-core Haswell CPU and Intel HD Graphics, ASRock H81M-ITX motherboard, 8GB of RAM, and 120GB Kingston SSD. The other system used for this reference Fedora Linux benchmarking was an Intel Core i5 3470 "Ivy Bridge" system with an ASRock Z68 Pro3 motherboard, 8GB of RAM, a 64GB OCZ SATA2 SSD, and the i5-3470 features integrated HD Graphics 2500.
All settings for each Fedora Linux release were using their stock settings. All benchmarking was handled via the Phoronix Test Suite software for its automation, ease-of-use, and guaranteed reproducibility of results.