I am not sure if you've isolated/know the cause yet, but there are constantly lag-spikes on DayZ XBOX. Randomly the game just comes to a complete halt, no audio, no movement, and stays that way for typically 3-5 seconds. It then returns to normal. If you're driving, there is a 90% chance you'll crash.
One thing I noticed is that anytime the lag-spike happens, the weather changes. Typically changes in the following manners:
1) Clouds suddenly get very thick once the game resumes (less blue skies)
2) Wind either gets stronger/louder or quieter/less impactful
3) Environmental sound changes (goes from chirping to crickets)
I am pretty sure this is due to the sped up time on the server. Just wanted to point that out in case you didn't know the cause yet.