In my experience there's a roughly 1K memory cost for each thread under NETMF. As for the time required to allocate a thread, if you're contemplating questions like that it's probably time to do a bit of reading on embedded systems best practice. I'm not mocking you, there's quite a bit of hard won lore that can save you heartache and hassle.
Case in point, the thread thing. If you want reliability you have to guarantee maximum resource demand. If you're going to say "no more than 5 threads" then you may as well start all five as part of your initialisation process, and allocate all the resources they're going to want.
If you can't do that then you can't guarantee the stability of your system under load. A side affect of this is that the time required to start them is irrelevant to the responsiveness of your system, although it does affect boot time slightly.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.