Yeah... the 5X does have a noticeable delay when you tap the shutter button.. and I am not referring to the exposure time on HDR+ pictures, straight up, HDR+ off pics, there's a like a drum beat between press and picture. I really don't know why, either. Sure, you could say that it has a processor that is slower than the 6P, but the LG G4 has the SD808 as well and that can rip off a shot far faster.
And if memory serves me right, 3rd party camera apps are much quicker to get the shot off. So its something about the Google Camera and the 5X... and I don't suspect it'll ever get fixed at this point. Though, maybe I'll load up the 4.2 port to see.... if they got it to snap right away (which it SHOULD be able to do)...
Oh, don't hold the HDR+ processing speed against it... The Nexus devices use an HDR method that is actually extremely processor intensive when compared to the other phones... and does a far better job of reducing noise without degrading the shot's original detail. Quality is worth a little bit of time.