Carl-Daniel Hailfinger [off-list ref] writes:

Can one namespace DoS other namespaces' access to the routing cache?
Two scenarios come to mind:
* provoking hash collisions
* lock contention (sorry, haven't checked whether/how we do locking)

My initial expectation is that the protections we have to prevent one user from
performing a DoS on another user generally cover the cases between namespaces as
well.

Further in general global caches and global resource management is more efficient
then per namespace management.

Eric