For a long time, AMD's drivers and the performance have been subpar compared to Nvidia's drivers for OpenGL. This is one of the reasons why it had developed the Mantle API as it wanted to have a head start in low-level graphics.
However, things could be changing for the better soon. In the newest 22H2 Insider builds for Windows 11, Microsoft is offering the AMD pre-release 31.0.12000.20010 UWP driver and the driver package also comes with the 22.05 OpenGL beta driver which massively boosts the performance of AMD GPUs in OpenGL applications. The driver was discovered by members of the Guru3D forum who have been playing around with it. This upcoming driver will be based on the next-gen Windows Display Driver Model (WDDM) v3.1.
Here is a screenshot of the driver details using TechPowerUp's GPU-Z provided by Guru3D member "The Creator":
A number of tests in synthetic benchmarks were also run with this driver and using the OpenGL API renderer, the performance difference is very significant. First up, we have Unigine's 2013 benchmark Valley which sees a performance boost of nearly 55%.
Up next, in the more modern Unigine Superposition, the performance difference is more than 33% in favor of the upcoming 22.05 OpenGL driver.
Interestingly, though, the driver seems to lose performance in the much older Heaven benchmark, indicating that more optimization may be necessary for very old applications and games.
While the above tests were run on an RDNA 2-based Radeon RX 6800 XT, the first-gen RDNA GPUs will also get a healthy boost it seems. Here is a screenshot of Superposition run on a Radeon RX 5700 XT.