I remember a few weeks ago the queue was backlogged over 1000 transactions and it took 3 days to get some of my payments and transactions though.
It has less to do with rushing miners, and more with 0.3.21 version which restricted sending free transactions. Unless you modify the code or use older version (and then you'll still have problems with nodes refusing to relay them), you cannot send a series of spam transaction which were frequent a few weeks ago. Also, the Faucet and pools went to sendmany transaction which significantly reduce the network burden.