Some additional information for the devs on locating the source of this FPS drop which I'm also experiencing:

A: It worsens the moment someone spawns in your proximity (was absolutely reproducible with two buddies of mine).

B: Using the tip from the forum member "Droopy Piles" who stated:
"I CAN CONFIRM THIS WORKS!!!

goto C:\Users\YourUserName\Documents\DayZ"
there is a .cfg data - open it and run it with editor.

scroll down till u find this and change both parameters to 3:"
GPU_MaxFramesAhead=3;
GPU_DetectedFramesAhead=3; " "

When applied, this seems to fix the problem, but really just delays it. You won't have an FPS drop for a bit, maybe 15 mins, but that's no definite time, and then it starts again just like without the fix.

Hope this helps.

I can confirm this as well. I was badly hurt and lost a lood of blood. After I was given saline, the colors returned, but the vision stayed blurry.
The workaround with accessing the video settings works for me, too.