I don't know how, but my frame rate went from a solid 60+ for the first 25-30 minutes of a game on my previous gfx settings to less than 20 unless I go low-to-mid gfx.
Someone mentioned that mods can become unstable or incompatible with new releases and cause this. I turned off ALL my mods and it returned to a normal frame rate for my PC (i5-4690K @ 3.8GHz w/ 2x GTX 770s)....
Is this just luck or did the recent lobby release actually cause this issue?