However, this doesn't appear to be the only cause for the performance drop when upgrading Ubuntu 14.04's graphics stack. Other regressions have also been reported by other users of the open-source AMD driver. "This is not completely from HyperZ and so still worth investigating. We have reports from Luke and dungeon on this forum that confirm there's another regression besides the intended hyperz change. Luke specifically tested it, dungeon's case is media apps that do not use the Z buffer." There's more comments in this forum post about the issue unrelated to HyperZ.