I've got convinced to play 1pp more.

[Roachracer 8]

Nothing quite tightens your sphincter than playing in 1pp in the dark of night looting up remote village with new Zombie AI. :o

[scriptfactory 620]

It's probably a matter or degree. The more you see the more your brain has to anchor onto. I honestly don't know but imo the biggest factor is frame drop/jitter. I'd guess a constant 20fps would be less troubling than 10 then 50 then 20 fps in quick succession.

 

Can confirm. I am a big ego-shooter enthusiast (since Wolfenstein 3D). I play other comparable games in first-person mode. This is the only game that makes me feel physically ill. I haven't had head bob or post-processing enabled since Dec 2013. I believe it is directly related to the lack of framerate stability, the strange perspective warping (regardless of FoV) and the janky character movement in 1PP.