I have heard from a Carl Pei interview that the camera is the reason for the phone having 6gb of ram because it snaps 4 photos at the same time we snap one photo. The phone then automatically chooses the best one photo of those four photos. I reckon that is also a probable answer due to the lag you are experiencing.
No, this is not the answer for the "lag". Why doesn't it lag in good lighting then?
I already gave the correct explanation for this.
As an example: I don't know if you have experience with the OnePlus One. It also started lagging much heavier in lowlightconditions due to the low shutter-speed.
Eventually, Sultan released his modded camera hal which forced the camera to not go below 1/30s on the shutter-speed.
The result was a perfectly fluid viewfinder regardless of the lighting conditions.
I am only talking about the fluidity of the viewfinder here. (Shutter-speed and video-framerate is a whole different story not to be mixed-up here...)
I've seen this interview too,
but I don't agree with him that it takes the best of these 4, instead I think that it somehow combines them into one.
This often results in more blurry pictures, even in good lighting!
Check this video I did on this issue:
http://www108.zippyshare.com/v/KidtanPE/file.html
As you can already see in the video, all images were taken without HQ or HDR. You can clearly see this when taking a picture and quickly swiping to the gallery.
For an instant, you will see the unprocessed picture which quickly changes as processing is being applied! Sometimes to the worse though :/
This gets more pronounced the more the ISO level goes up on a shot.
I was holding my phone as steady as possible and you can see that the shots which are displayed first look sharp before postprocessing.
So how can this be explained when, as Carl says, "the camera takes the best out of 4 shots"?!?
