Added another 5% or so on all my rigs with older cards using the -i 2 switch.
On my Rigs with newer cards, such as the RX series, I actually seen a slight decrease versus version 2.0. I have tried all three intensity levels and even the -i 2 gives a bit less sols and the CPU usage is greater than in version 2.0. I am still playing around as it might have been my lowered clocks, but it seems this version was geared more toward the older cards.
I get about 2-3H/s boost on all my 470s and 480s, 4GB and 8GB versions, most sapphire some others. Just have dual cores, mostly celerons, one APU. You can try setting ZecMiner priority to above normal in task manager, it may help slightly. Also check if other processes are using much CPU. Surely there is more room for improvement on Polaris, but I got boost from 1.1 -> 2.0 -> 2.1
Thanks for the suggestion. I might play around a bit more, but according to Claymore's last post this version was mainly for the older cards anyway. I don't run anything but the miner and VNC on the rigs once I get them dialed in, so I doubt setting the task priority higher will help much, but I will test it out anyway.