https://github.com/libbitcoin/libbitcoin-node/blob/master/src/poller.cpp#L155

What do you think is a good way to rate limit "getblocks" requests?

The problem with this is that if you have blocks 1, 2, 3, 4, 5, 6, ...
and if block one is delayed then blocks 2, 3, 4, 5, 6, ... will all be
orphans sending multiple "getblocks" requests flooding the other node.

Also if there are connections that drop often, then the current check
will stop new "getblocks" requests to be issued causing the blockchain
to fall behind.

There needs to be a newer more robust way of allowing getblocks requests
without allowing a flood of requests caused by many orphan blocks.