Phoronix published a review on the Windows 10 vs. Linux 4.15 + Mesa 17.4-dev Radeon Gaming Performance
A quote from the article:
As we end out November, here is a fresh look at the current Windows 10 Pro Fall Creator's Update versus Ubuntu 17.10 with the latest Linux 4.15 kernel and Mesa 17.4-dev Radeon graphics driver stack as we see how various games compete under Windows 10 and Linux with these latest AMD drivers on the Radeon RX 580 and RX Vega 64 graphics cards.Windows 10 vs. Linux 4.15 + Mesa 17.4-dev Radeon Gaming Performance @ Phoronix