"We think we need a minimum of 15 [server side] FPS [with] 50 players, 2000 zombies, and 25000 loot items," explained designer Dean Hall in a recent Reddit post. "Our latest tests have all shown some runaway systems in the code we have to tidy up. The variable synchronization system that was developed for work with the network bubble, is checking the variables very often. We're optimizing this. Also, there are many string comparisons." It goes on like that for a few more sentences, but the key takeaway here is that there are very real, technical hurdles that must be leapt before the game can hit retail.
Despite this refreshing level of transparency, Hall refuses to assign a release window to the standalone version of DayZ. "If I start saying 'oh it won't be out then' people start asking me about the day after, and the day after," said Hall. "So it just encourages people to keep asking me when it is, and the "announced date" would be when I go 'yeah, it could be out then'."
Edit: This piece has been altered to specify that the "15 FPS" mentioned in Hall's message was not referring to the framerate players will see in game, but was instead referring to server side FPS.