[!IMPORTANT] The latest Unity 2021 release has a known blocking performance bug with HoloLens 2 if the project is using URP rendering pipeline.
For new projects using URP rendering, we recommend using latest Unity 2020.3.35f1 or later LTS with the latest Mixed Reality OpenXR plugin to avoid this issue.
If using other Unity releases, consult the known active blocking issues to ensure you avoid builds with other blocking issues.