karma dicing, ocean render-time displacement single threaded?

[Coz_y_not]

Is the Karma dicing / render time displacement of the ocean single threaded? 

If you look at the CPU chart (showing 2 frames), the actual rendering happens in the 2 gaps where all threads are at 100%

The spectrum bgeo is 36mb! and the mask 240 frame sequence is 230mb

There are three visible stages (% time per frame):

1. 50% of the time -> One thread at a time

2. 10-20% of the time -> Right before the they all reach 100% there is some dance there, not sure what that is

3. 30% of the time ->  all threads at 100% 

Do you have any idea of what is being done in each of these stages? the last being render because one done the image appears in the render directory.