I have something to add to my post as new stuff happened today ^^.
I spend the day looking for what can be the cause of the problem.
I do thinks that the compiler algorithm has changed and is less performant at dealing with circular references.
My method :
I started a new project and moved all of my components one by one. Doing clean build folder and recompiling at each feature I added.
At some point my build time jumped from 5 sec to 150sec with the addition of one file that uses some other structs I added.
When removing all functions, members that uses my custom time, keeping only Strings, Ints and Arrays. My build time came back to 5sec. Adding a single reference to a custom type that I know is dependent of other tipes (its a Backoffice Model) sends the build time to the 100+ sec.
Is It possible to get to the 13.2 build algorithm ? With that one it takes me only 30 sec to build the entire project.