After investigation I come to conclusion that arsbitcoins block/rate limit tcp connections and bitHopper tries to open new connections to the host until it runs out of free sockets. Disabling arsbitcoins helps, but I think there should be a better way for bitHopper to handle TCP timeouts/SYN-packets dropped by pools. I am not sure if http/1.1 keep-alive is implemented. But it could help to reduce stressing pools with huge load of new tcp connections.
You are correct, ArsBitcoin does rate limit/block TCP connections. Why does BitHopper needs to open up 1000+ TCP connections to my pool in order to mine? It seems to be just temporary, when trying to connect for the first time.... but yeah, its crazy. Occasionally I'll whitelist some of the IPs I see doing this, cause it doesn't seem to have too bad of an effect, but is this something that can be fixed?