I wrote a blog post about the work we did to make player builds in Unity faster: https://blog.unity.com/technology/accelerating-player-builds-with-incremental-build-pipeline
@jonas great writeup! And extra love from me for mentioning the Android incremental deploy, hope PRAM is still live and kicking :)
Didn't think at the time that whole project would have been _that_ massive, but we ended up moving mountains didn't we :)