My personal workaround... yesterday, I had used GNOME3 Classic which reduced the freezes down to "every3 hours". ;-) Today morning, I've downgrades the kernel back to the previous version and I'm back to GNOME3 and Firefox for 2 hours now. No freeze so far...
What I've done is: aptitude install linux-image-3.16.0-4-amd64=3.16.7-ckt20-1+deb8u4 linux- headers-3.16.0-4-common=3.16.7-ckt20-1+deb8u4 linux-headers-3.16.0-4- amd64=3.16.7-ckt20-1+deb8u4
