There’s some things that could be done in order to speed up the build time.
Changing the make -j<value> could help in regards to speeding up builds. I’ve seen different posts in regards to whether the value is related to CPU/Cores or memory.
I decided to ultimately try this :
I set my configuration file : .config in the B2G to J10.
It did seem to make a difference.
There’s some other interesting options listed here : https://developer.mozilla.org/en-US/docs/Configuring_Build_Options
What would be interesting also, is to use some farm nodes to build using :