I have had the S5 for 3 weeks plus and the one thing that really annoys me is the random lag. Sometimes it takes ages for the camera to fire up and shoot its first shot, by which time the moment is lost.
So I have been experimenting with various combinations to try and get the quickest first shot time. So what you have to do is install nothing. Well, it felt like that at first.
So, first up, in home screen, press recent apps list and select close all. In settings, lockscreen remove the weather, help, pedometer options and anything else which will need the phone to find other information from other apps. Under security select no security, swipe. Select include camera shortcut in lockscreen. Now this isn’t ideal having no security so in the long term this is not really recommended.
Open camera, press home key. Make sure camera is in auto mode with HDR off and the same for picture stablisation. You can always turns these back on.
Now, from the lock screen you can swipe the camera shortcut, and 9 times out of 10, the camera will be open and focused in less than a half a second.