My friend and i have the same 6.1 devices but when we open the camera it will be freezing lagging too much sometimes i can't even take a single photo or sometimes i can't even to access the third party cameras also, hope you're fixed soon.
I also have this issue with my phone despite the latest camera update. Camera is laggy and when its opened from Whatsapp the screen stays black and have to switch between back en front camera. Still its laggy buy al least i could take a photo.
Try Google Camera apk for good Portrait and Google Motion Features.
is very good as compared to old one.Its having portrait features very good.Lens Blur not working but we got portrait mode very useful and google motion is fantastic.Try Everyone This Google Apk Very nice.I am fall in love.