For those coming upon this, the shortened answer is so:
‘Fetching engine’ time relates to the deviation of the engine from last build, so to reduce time spent, remove unnecessary extensions and don’t modify engine every build.
Hopefully, someday, Defold will add extension caching which will optimize this problem out of existence.
I am wondering what I can do to optimize the time spent “Fetching engine” (I presume to mean building project), as it is currently quite lengthy for my project. This is not about the performance of the exported game, but the build time.