It seems that auto detection failed and set treads count to 5 (that's why cpu usage 66% - 5/8), but for your cpu it would be better 4, try to set it manualty "-t 4" for command line or "threads: 5" in config file, it should increase hashrate
The command line didn't work, it didn't care of my setting. I've set to 4 in the config.
The hashrate displayed by the pool has big variations, between 33 and 200 H/s, having the 6h average 90 H/s and 3h average 77 H/s. So the setting change doesn't seem to help.