"The Right Way" to use Unity, aka "Performance by Default, for now!"

Is there a guide to using Unity in its current state, akin to what the future holds with regards "Performance by Default" in the eventual ECS version of Unity?

In other words, somewhere to learn the 'right' ways to use Unity, wherein performance and efficiency is optimal.

In other, other words:

If playing to strengths of existing Unity, how is a project best architected?

 

There are best practices and performance tutorials right here on the page:
https://unity3d.com/de/learn/tutorials/s/best-practices
https://unity3d.com/de/learn/tutorials/topics/performance-optimization
Are you searching for something more specific?

 

YES!

And no...

I want something that says:

"here's the best way to consider architecting your game, for performance and efficiency (meaning mobile)"

From the perspective of loading screen to levels, and then on down to objects in levels.

But primary at the level level of consideration.

 

At this moment the best resource for ECS is ECS forum. Plus all the videos where Unity employes talk about it.

The easier way is to wait for ECS to be more mature and this all will be documented.

 

I specifically don't want ECS stuff, I'm trying to consider Unity, as it is now, not as it will be.