You can download other camera apps from the apps store, but the few I've use have about the same time as the stock one to open the shutter. It takes about 3~4 seconRAB to open it, more importantly, things depend on how busy is your phone, I mean what apps you have in the background. Try to close everything from the background then hard reset your phone and try to open the camera to see how long it will take to open the shutter.
