For some reason the GUI is not showing up for me in 3DGS.cpp. (I checked out the repo, made a build folder and built with Ninja, then launched ./apps/viewer/vulkan_splatting_viewer).

I still have a VulkanSplatting build from this Wednesday though. In VulkanSplatting, when looking at the Lego scene from above with the default window size, I'm getting just below 1 ms for the sorting kernel and just above 1 ms for "render", everything else is too small in the graph to register. But it only displays at a handful of fps, so it seems quite some time goes unaccounted for.

Maybe spinning up Instruments could give some more insights into what's happening? I tried `cmake -G Xcode` to have that setup easily, but the Xcode CMake generation fails with

    CMake Error in src/shaders/CMakeLists.txt:
      The custom command generating
    
        3DGS.cpp/build-xcode/shaders/shaders.h
    
      is attached to multiple targets:
    
        shaders
        xcode_shaders
    
      but none of these is a common dependency of the other(s).  This is not
      allowed by the Xcode "new build system".