Radeon Software 18.10 vs. Mesa 18.2 RADV/RadeonSI Benchmarks
With the OpenArena open-source game, the RX 580 had a minor advantage with the RadeonSI Mesa 18.2 driver while the RX Vega 64 was significantly faster. Though on the frame timing side, there were spikes slightly higher with Mesa.
Serious Sam 3 BFE with Vulkan found the RX 580 to be faster on RADV while the 18.10 PRO driver stack was faster for the Vega graphics card.
The PRO driver stack was also faster for The Talos Principle.