Someone may have missed these articles from the ECC blog, may have already forgotten or come back later. I am still relying on my memory:
Scalability and Recursion
Recursive proof composition allows a single proof to attest to the correctness of practically unlimited other proofs, effectively allowing a large amount of computation (and information) to be compressed. This is an essential component for scalable Zcash, not least because it allows us to horizontally scale the network while still allowing pockets of participants to trust the integrity of the remainder of the network.
from: