With both the MP3 and Ogg encoding, OpenSuSE 11.1 RC1 was the slowest. Whether this is due to debugging options being enabled in this pre-release of OpenSuSE or not, we will have to wait until the final release is available. Ubuntu 8.10 on the other hand was the fastest each time with Fedora and Mandriva just being slightly behind.
When compressing a 2GB file with Gzip, Mandriva and Ubuntu were both noticeably faster than Fedora and OpenSuSE. Fedora 10 was the slowest in this test.