Sorry Dennis, the topics have been set for sometime now.
This is a *very* broad topic with so many permutations. I think, rather than trying to come up with generalized sokutions, this is something you can discuss during the Implementer one-on-one meetings. An Implementer can then address your specific needs.
There is no “one size fits all” here. Some may have to add an additional site at 40 threads, while others may be OK at 90 threads.