Pretty much everyone has this issue. It's just too early in the alpha and not a big enough company / engine to expect too much at this point :) optimisation will be the last thing done before release sadly. Perhaps adjust your fan curves if that's something you are comfortable with.

Its been like this for me since the begining, GPU and CPU loaded almost to 100% and 100 degrees temp(rig similar to yours), but the game still runs like shit. Very poorly optimised - if at all, lol.