Platform switch freezes for larger projects

I have a larger project I'm working on using Unity 2018.1.2f1 on the latest macOS. Cache server has been a huge help in getting multi-platform work done by a small team, but I'm lately running into a problem I haven't had before. After pressing Switch Platform, especially when switching to Android, the whole editor seems to freeze for a long time. Here's the Editor logs for the part I'm talking about:


Refresh: detecting if any assets need to be imported or removed ... Refresh: elapses 0.375206 seconds (Nothing changed)
Determining assets that need to be reimported for target platform ... Refreshing native plugins compatible for Editor in 3.25 ms, found 7 plugins.
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32.dylib
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32.so
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32.bundle
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/Kernel32
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32.dylib
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32.so
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32.bundle
Fallback handler could not load library /Applications/Unity/Unity.app/Contents/Frameworks/Mono/lib/libKernel32
Connect to CacheServer localhost:49510
Disconnect from CacheServer
12.924501 seconds.
<Freeze here ~10 min>
Hashing assets (0 files)...
0.000 seconds
file read: 0.000 seconds (0.000 MB)
wait for write: 0.000 seconds (I/O thread blocked by consumer, aka CPU bound)
wait for read: 0.000 seconds (CPUT thread waiting for I/O thread, aka disk bound)
hash: 0.000 seconds

Hashing assets (2412 files)...
12.934 seconds
file read: 5.982 seconds (8018.949 MB)
wait for write: 5.878 seconds (I/O thread blocked by consumer, aka CPU bound)
wait for read: 0.316 seconds (CPUT thread waiting for I/O thread, aka disk bound)
hash: 12.003 seconds
Connect to CacheServer localhost:49510
Unloading 10961 Unused Serialized files (Serialized files now loaded: 0)
System memory in use before: 0.79 GB.
System memory in use after: 0.79 GB.

Unloading 10930 unused Assets to reduce memory usage. Loaded Objects now: 10813.
Total: 40.249345 ms (FindLiveObjects: 2.943888 ms CreateObjectMapping: 1.709117 ms MarkObjects: 32.366985 ms DeleteObjects: 3.228416 ms)

Updating Assets/PostProcessing/Editor Resources/Monitors/VectorscopeCompute.compute - GUID: 45de9ff58691e934c9810dc23de2ba50...
done. [Time: 155.041355 ms]
Updating Assets/PostProcessing/Editor Resources/Monitors/HistogramCompute.compute - GUID: 51b7e4b4448c98f4a849081110fd6212...
done. [Time: 11.579779 ms]
Updating Assets/PostProcessing/Editor Resources/Monitors/WaveformCompute.compute - GUID: 9d9b886f7a8fe7b4baf56624c42e3420...
done. [Time: 9.246134 ms]
Updating Assets/PostProcessing/Resources/Shaders/EyeHistogram.compute - GUID: e213272ad8ff213409a6e13b5c26b4e4...
done. [Time: 13.929882 ms]
Unloading 81 Unused Serialized files (Serialized files now loaded: 0)
System memory in use before: 431.2 MB.
System memory in use after: 431.8 MB.

Unloading 81 unused Assets to reduce memory usage. Loaded Objects now: 10476.
Total: 27.996243 ms (FindLiveObjects: 2.004250 ms CreateObjectMapping: 0.307822 ms MarkObjects: 25.635115 ms DeleteObjects: 0.047975 ms)

Disconnect from CacheServer
Refreshing native plugins compatible for Editor in 16.71 ms, found 7 plugins.
Preloading 2 native plugins for Editor in 1.76 ms.

----- Total AssetImport time: 533.444336s, AssetImport time: 2.050560s, Asset hashing: 12.934569s [7.83 GB, 619.962646 mb/s]
----- Cache Server detail: CacheServerIntegrate time: 2.000513s, CacheServer download: 10.961905s [2.61 GB, 244.088470 mb/s]
----- Cache Server detail: Total assets requested: 2412, Cached Assets: 2408, Not available: 0, Not supported: 4.
----- Cache Server detail: CacheMove: 1.767653s, CacheDelete: 0.000000s.

What's happening here? Is this a bug or intended behaviour? How would I go about speeding up the process? If it's an inevitable part of switching platforms, could we increase logging and maybe even show a progress bar in the UI? It took me a few days until I realized that Unity hadn't frozen permanently, it's just a slow running silent process that I need to wait for.

Also, if this is a bug, what's the best way of sending a bug report for a proprietary project with ~10GB assets?

 

I am still getting the same issue on 2018.1.3f1. I've noticed the same occurrence when building via jenkins and the command line.