How to avoid slowly tyCache in BirthFlow? Which are important parameters?

[Alexx31]

Hello,

I have a big destruction scene of multiple caches, some start getting extremely slow, when reading them into a BirthFlow.
I'm struggling how to proceed with this project.

As in thread before written I have enabled "Subframe Scale down" to get the Cache properly read. 
(what exactly is that?)

- Are there rules how to keep a fast workflow? Is "time step" important when reading a birth flow? 
Does it slow down when it is anyway only cache with single frames?

Thanks for advice