Same issue here. See both AWII Snapshots. Faster one is Win11, slower one is latest Garuda Linux. Bug-Report also attached.
Funnily, power draw is so much lower in Linux when RT is enabled. Both OS limited to 240 Watts power draw, same OC.
Latest Proton-GE and Nvidia 570.
AWII set to 1440P all Max/Ultra with Ultra RT and DLSS quality.
nvidia-bug-report.log.gz (1.6 MB)
Just 44% performance in Linux. That really is a shame.