Unreal compiling for hours at 0.1% processor

Development Programming & Scripting C++
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1

Unreal compiling for hours at 0.1% processor. How to use 100%? This is not usable at all.
Thanks

2

That sounds a bit extreme so there could be something else wrong, but it may be I/O bound. You really want to have the engine (or at least the Intermediate folder, via symlinks) on an SSD when compiling from source.
You also need to be sure you have sufficient memory available - most of the build is accessing the huge precompiled headers that are generated, so if it’s constantly going to disk for these because of insufficient memory, that will kill your performance.

3

Another thing that happens (once) is compiling shaders, which will fork out to a shader compiler binary.
If you check processor utilization, is there some other process that uses all the CPU?
Another thing that can cause low CPU utilization and long compile times is too little RAM; if the system starts paging, it’s basically all over.
Make sure you’re have spare RAM, and that the system is not doing any paging/swapping!