Because of the problem with a good, fast and working nvidia driver, I’ve tested the actual beta driver from Nvidia. After installing it on my system (Dell M4300, with zen-sources 2.6.29-r3 running fine on it) everything seems to be fine. But there was the first fault. The character set in the Terminal swaps. The next serious error was restarting the X-Server or crashing the whole system while surfing with Epiphany. So I downgraded my system to nvidia-drivers-180.29 again as mentioned here. It seems Nvidia has to do some work on it, still we have another working release. Stay tuned, we will test it and tell you our experience with any new driver we found from Nvidia.