1.7.0 Patch - Major computer speed reduction

Just updated to 1.7.0 - now my computer slows down to 1-2 fps as soon as I load a game, be it single player creative/survival, or as soon as I join a multiplayer game.

Its not just a video issue - the computer itself bogs down massively. Even if I alt-tab out, and have Empyrion just in the background the computer chugs really badly.....

Everything was just fine prior to the update. Also, at the Empyrion main menu its all good. Only when I get part way through the 'loading' screen with the...

1.7.0 Patch - Major computer speed reduction