you should find the closest pool for your location to reduce latency. Higher latency can produce more rejected/stale shares. Your current rejected is at 4,3% and it is very high. Ideal valute is deeply under 1%. eg I am from the Europe and mining on the US pools produces a lot of rejected shares for me, mining on European pools reduces it to minimum = higher rewards from mining for me. Sometimes it is not very big difference but sometimes it can produce much higher rewards from the pool. And using the pool where you can adjust worker diff for your miner (to 0,20-0,30 shares per minute ideal) can really help.