As the title says, with vsync and immersive railroading installed, the fps go from 60 to 30.
Without vsync, it drops about 10 fps from about 80 to 70

I'm noticing the same on the temporary system I am using (as my main system is in for repairs [bad power socket]). This one has Intel HD Integrated Graphics.

I've improved the rendering system significantly over the past few updates. I am going to close this for now, feel free to re-open if you are still experiencing the issue

I am having trouble reproducing, what GFX card do you have?

R9 200 Series.
R9 280x specifically.
My brother has a GTX 960 and he has the same problems with vsync.

I should drop in my R9380 and give it a test