Phoronix published a review on the NVIDIA vs. Radeon Vulkan & OpenGL Performance With A Celeron, Pentium & Core i7

A quote from the article:

Here is an interesting OpenGL vs. Vulkan Linux benchmark comparison where I take two competing NVIDIA and AMD cards, the Radeon RX 580 and GeForce GTX 1060, and test the available benchmark-friendly OpenGL/Vulkan Linux games while doing these tests each on an Intel Celeron, Pentium, and Core i7 processors in looking at the performance scaling.

 NVIDIA vs. Radeon Vulkan & OpenGL Performance With A Celeron, Pentium & Core i7 @ Phoronix