I noticed the same problem after there settings reset to high since the last patch..
And of course, I've also that fps drop on my notebook and no clue where it could come from :/
I was like 120 fps before the patch and now I can't go higher than 60-80 fps

And when there is smoke, I can even freez !!
WTF seriously.
From the last patch, they had to correct the smokes that could disappear from alt tab, that mean they probably changed something on graphics/smokes display..
It's only observations, but it's fucking annoying to see your fps drop or just the fact that your graphical configs get reset -_-'