Google's Pixel cameras are outstanding, and a lot of it has to do with some downright clever software in the new camera app. That zero shutter lag experience is one of those things you don't know you care about until you see someone else with it, and when you combine that with the overall quality of the images you get from a Pixel it's easy to feel the urge to click the purchase button.
Charles Chow has been working hard to make the Nexus cameras feel a little lighter, and after poking around at the camera software Google has been using in the Pixel phones he has cobbled together a solution for anyone with a 5X or 6P to sideload for themselves. Camera NX V4 implements the Pixel tools for zero shutter lag and that background processing for HDR shots, making the Nexus cameras feel a whole lot faster. You aren't going to get an exact compare with a Pixel, especially since some of what is happening to make that camera so fast is hardware, but it's much faster than what you've got right now.
Keep in mind this is not an official app from the Play Store, and has its own bugs you'll find while trying to take pictures. This is mostly for folks who want to tinker and see how much better this camera really is, but there's a good chance no matter who you are you'll be impressed with the results. If you want to install the app, head over to Chow's site and scroll all the way to the bottom. Read to find the right link for you, and be sure to drop into our Nexus 5X or Nexus 6P forum to share your experiences!