Ubuntu 9.04 and its open-source ATI stack were slightly faster than Ubuntu 8.10 when looking at the GtkComboBox widget performance in GtkPerf. The Jaunty Jackalope was about 7% faster.
The GtkDrawingArea Pixbufs performance had really sped up with latest development release of Ubuntu 9.04. It took 56.22 seconds for Ubuntu 8.10 to complete this benchmark, but Ubuntu 9.04 Alpha 6 required just 6.49 seconds.
The GtkRadioButton performance was nearly twice as fast in Jaunty over Intrepid.