Probably because it’s got an absurd 10,000 line switch statement. I’m working on extracting that into manageable functions over time, but, well… 10,000 lines.
Be glad that we’ve trimmed down itypedef.cpp, as well (by moving most things out into JSON files). I recall one of the Windows devs saying that compiles were taking ~35 minutes for him, or ~15 if he disabled optimizations on that file.