Network trouble inside US-East combined with a call that involved a lot of round trips.
I was asynchronously sending maybe 50 messages out and waiting for replies. In US-East, the standard deviation of network latency went way up, meaning that while most of those messages return in 2-3ms, a few took up to 50. It turns out that I didn't need all 50 responses anyway, so I just set a timeout of 10ms and did the best I could with whatever messages did return.
I was asynchronously sending maybe 50 messages out and waiting for replies. In US-East, the standard deviation of network latency went way up, meaning that while most of those messages return in 2-3ms, a few took up to 50. It turns out that I didn't need all 50 responses anyway, so I just set a timeout of 10ms and did the best I could with whatever messages did return.