Batch/rate-limit sending transaction lists over network

[catbref]

When a node receives several new unconfirmed transactions,
it then broadcasts each 'new' transaction signature singly to all its peers.
Ideally, these should be batched and sent after a short delay (e.g. 10 seconds) to reduce network load.

In addition, requesting unconfirmed transactions results in a huge response from peer (~18KB).
This should be converted to a potential list-delta algorithm?
Futhermore, maybe nodes shouldn't request unconfirmed transactions until they are up-to-date?