My up to date system is Ubuntu 16.04.03 LTS with 4720hq and dedicated 960m. Doomsday version is 2.1.2423.
I can only have something like sub 20 fps at the open area of the 'No Rest for the Living' expansion pack's third level 'Canyon of the Dead'.
I have vanilla settings and zero packages loaded. Resolution is full hd. Why is the frame rate so slow?