With OpenArena 0.8.8, the Mesa 9.1-devel performance is only slightly higher than Mesa 9.0. This game's performance hasn't matured much since Mesa 7.11, only being up by 12.5% in the past year and a half.
World of Padman isn't a wild mover, but its frame-rate is up by 6% with the forthcoming Mesa release. Since Mesa 7.11, the high-end Ivy Bridge graphics are faster by 18% over its Mesa support lifetime.
There were rather large deviations in the Prey (id Tech 4) performance in the Mesa releases prior to 9.1, with only indications of minor performance changes from release-to-release.