unity conversion single threaded?

Unity is still converting a old 5.x project to 2017.2. It's taking a while so I opened up the task manager to see what's going on and I was quite surprised : the editor and other editor spawned processed total less than 6% cpu usage.
I'd think that shader compile and image or audio conversion are not interdependent and so would spam all the cores of this 1700x no?
Anyway, seems like a bug so I logged this 948980

 

Oh I see, out of curiosity which assets conversion uses more than one core? Also I noticed they are done sequentially, why is that?

 

There's work-in-progress to redo the entire asset pipeline so it follows dependencies etc. vs. ordered by asset types. So, that should address both the sequencing and multi-core usage in one go.