Multi-volume is currently faster because it does not use shading yet, but therefore the image quality is lower.
Increasing TDR delay fixes issues that you described above. If it did not help then I would recommend to try it again. It is somewhat tricky to set this registry value, because if you temporarily set it to 0 (e.g., you create the registry key but not set the value yet) then it shuts down your system, as TDR delay = 0 causes immediate TDR timeouts everywhere.