It turned out to be an LOD problem: when going from Oculus to OpenXR, I had to scale everything down by 10 times, which brought the objects ‘closer’ and they were using a higher res LOD. For all my meshes I regenerated and messed with the distances and it solved the performance problem.
Sorry it ended up being unrelated, but if anyone else is porting a project from API to API it might be useful.
What? Switching API’s won’t have that effect. Something else must have happened.
The project (as I received it) had a world-to-meters of 1000, and using OpenXR I had values returned that were smaller than expected (in cm instead of Oculus’s mm? Not sure about the WHY here). After turning the world-to-meters back to 100, I had to mess with everything’s scales. THAT scale change I think lead to the LOD issue, which lead to a performance issue, which lead to ASW. Sorry for the incomplete information.