Hello Matthew,
thanks for your comment. It did indeed fixed the slow build issue. We now have around 20% faster build times, as expected.
Nonetheless we have an error when we build the game while the editor is running. Here is the log:
1>------ Build started: Project: MyGame, Configuration: Development_Editor x64 ------
1> Compiling game modules for hot reload
1> Performing 3 actions (4 in parallel)
1> Module.MyGame.cpp
1> [2/3] Link UE4Editor-MyGame-6199.dll
1> [3/3] Link UE4Editor-MyGame-971.lib
1> Creating library C:\Projects\MyGame\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-MyGame-6199.lib and object C:\Projects\MyGame\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-MyGame-6199.exp
1> Creating library C:\Projects\MyGame\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-MyGame-6199.suppressed.lib and object C:\Projects\MyGame\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-MyGame-6199.suppressed.exp
1>ERROR : UBT error : Failed to produce item: C:\Projects\MyGame\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-MyGame-971.lib
1> Total build time: 14.81 seconds (Local executor: 0.00 seconds)
1>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.MakeFile.Targets(37,5): error MSB3075: The command ""C:\Program Files\Epic Games\4.15\Engine\Build\BatchFiles\Build.bat" MyGameEditor Win64 Development "C:\Projects\MyGame\MyGame.uproject" -waitmutex" exited with code 5. Please verify that you have sufficient rights to run this command.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
Note that it does not prevent the editor from successfully loading the new DLL, and apparently it does not prevent me to put breakpoints and step in the code when I attach the debugger to the editor.