I am not sure that would work either. If I understand correctly, the root cause of delayed responses is because more requests were sent on that link due to has

I am not sure that would work either. If I understand correctly, the root cause of delayed responses is because more requests were sent on that link due to hash collisions, which delays connections on that link. So, wouldn't "most recent request sent" correlate well with "most recent response received"? EDIT: Also, this seems like a classic load balancing problem: Simply picking the least loaded connection would have been sufficient. The response time on each connection could be computed either explicitly (a running average/standard deviation of RPC finish times) or implicitly by checking the queue backlog at any time (the queue backlong being a first-order statistic).