Prolific Mesa developer Marek Olšák is looking to tackle what he thinks is the "biggest performance bottleneck at the moment" for the RadeonSI Gallium3D driver.

Marek explained when seeing some of our regressed DiRT Rally Radeon Linux results, "I think the problem there is that Mesa git started uploading descriptors and uniforms to VRAM, which helps when TC L2 has a low hit/miss ratio, but the performance can randomly drop by an order of magnitude. I've heard rumours that kernel 4.11 has an improved allocator that should perform better, but the situation is still far from ideal."

Marek has a plan for hoping to solve this problem. The technical details can be found via this mailing list post. From the discussion that ensued, it looks like Civilization VI is another game affected by this performance bottleneck.