First of all I'm the lead engine developer of the game Cattle and Crops. We use a heavily modified OpenGL engine based off Terathon's C4 engine.
We got many reports about a really bad OpenGL performance with our game on AMD cards especially on Radeon 480 RX.
I told our users to try the public Tombstone 2.2 engine demo which is the successor of the C4 engine and very similar.
Tombstone runs with 30-50 fps on AMD cards and even on my newest installed Sapphire Nitro Radeon RX 580 while Nvidia's output with a Geforce 1070 is 60-100 fps average.
I tried to find the cause of this issue and it seems like the AMD OpenGL driver is CPU bottlenecked when send drawing commands.
The GPU runs with half of the clock for the most of the time.
Too bad the new Radeon GPU Profiler only supports DX12 and Vulkan but it's really cool with those APIs.
It seems that other OpenGL users have the same problem.
I uploaded some screenshots of the user reports with Tombstone 2.2 and our engine here:
I've been hacking with OpenGL for 17 years but now it seems like to be a dead end.
Is it really necessary to switch to Vulkan or DX11/12 to get a good performance out of AMD cards?
Thanks in advance.