Really hope they patch the memory leak ASAP as it's annoying have to close the game down every 45-60 minutes to maintain a decent framerate
I'm not at home to test... but... do you overclock your CPU/GPU? If you do - try resetting it to stock and see if it happens.
I know I had one game which would have issues when overclocked (even when stable!) and resetting it to stock fixed it.