High UObject discovery time during build

I’m getting a UObject discovery time of over 5 seconds when building.
In the test scenario where I got this number, I’ve done a full rebuild, then added a space in one of my comments in the ClientGameMode.cpp file.

After running the steps in Project.Build.cs
It will wait for a while and print : UObject discovery time: 5.1137333s
Then proceed to run Parsing headers for unrealEditor.
Taking a total of 22 seconds in the end to compile this tiny change.

What is causing this, and how can I resolve or reduce it?