EXTREME FPS DROP UNPLAYABLE AFTER UPDATE

After updating to the new and "improved" client i have noticed that when i go into games no longer do i get the great 300 fps but a measly 20 fps continuous. the only way to sort of remedy this is to close the other client (fancy looking one as stated in the link) and it brings me to between 55 and 60. Send help and yes ive done clean reboot and everything else in order to fix this problem.