UI: Note that Vulkan can have VR performance issues

Currently VR can have suboptimal performance when using the Vulkan
backend (#138977). Jereon has run various experiments and was unable
to resolve the issue. So in the meantime work on Vulkan VR performance
has been delayed until Blender 5.0.

Since Blender 4.5 is likely to release without a fix for the VR
performance issue. This commit adds an explicit note about it to the
user preferences.

Pull Request: https://projects.blender.org/blender/blender/pulls/139519

scripts/startup/bl_ui/space_userpref.py

@@ -703,6 +703,7 @@ class USERPREF_PT_system_display_graphics(SystemPanel, CenterAlignMixIn, Panel):
             col = layout.column()
             col.label(text="Vulkan backend limitations:", icon='INFO')
             col.label(text="\u2022 USD/Hydra is not supported", icon='BLANK1')
+            col.label(text="\u2022 Low VR performance", icon='BLANK1')
 
 
 class USERPREF_PT_system_os_settings(SystemPanel, CenterAlignMixIn, Panel):