The one I have been bitten by is the TCP retransmission timeout (RTO). This is the time TCP will wait for an ack before resending some data. This number has t

The one I have been bitten by is the TCP retransmission timeout (RTO). This is the time TCP will wait for an ack before resending some data. This number has to be somewhat conservative because if the RTO is less than the normal round trip latency TCP will be constantly resending packets. Normally the RTO is set to 200ms. This is conservative in case you have long distance TCP connections. However when your systems are in a same data center environment where round trip times are sub-millisecond the default is two orders of magnitude too high and should be tuned down.