BF4 runs with the same simulation and network rate setup as BF3. There is no reason to believe that BF4 wont play as well as BF3 did (or better), once we've managed to fix these bugs. That is our primary focus right now.
Assuming this is correct, this can be considered as confirmation that there has NOT been any change in the Tick Rate from BF3 to BF4 and the fairly big decline in "netcode" in BF4 is due to bugs that DICE have not yet been able to fix. Please consider this before accusing DICE of running a lower Tick Rate in BF4 than in BF3 and before asking DICE to increase the Tick Rate to BF3's levels. It isn't helping anyone to complain about things that are not even correct. However it could still be argued that the "netcode" in BF4 may improve if the Tick Rate was increased. I still believe that at it's core the game is hampered by its slow update speed but I'm reserving my full opinion on this until we have additional clarification from sliced_lime as he has said he'll "try to" write up something more detailed about this issue. I'll leave my original post intact for posterity.
Definition: a simple explanation is that the "Tick Rate" is how frequently your game client is updated by the server you are playing on. At present, BF4 has a Tick Rate of 10hz, or 10 times per second. This is very low in comparison to other FPS games like Counterstrike which has a Tick Rate of up to 120hz. While it's not certain, the main theory is that EA and/or DICE set the tick rate at this low level to reduce the costs associated with server bandwidth usage. The 10hz Tick Rate introduces 100ms of lag ON TOP of any additional lag from individual player's connections.
As clearly shown in this excellent video (http://www.youtube.com/watch?v=QdjYmtgAqls
[youtube.com] NOTE: this is not my video), the low tick rate introduces a variety of problems into the game, the biggest of which is the "instant" kill problem. Because the game updates slowly, it's possible to be killed by a player before your game client can show damage which gives the appearance of being instantly killed. In reality, the other player hit you several times but because of the slow update speed it appeared as if you were killed instantly without any chance to react. Watch the video for more detail on this.
Consider a gun like the FAMAS with a 1000 round per minute fire rate. With a 10hz Tick Rate and the 100ms latency this introduces plus player latency, the game will always update slower than this gun fires meaning it's just not possible for you to receive the correct hit notifications if being fired on by this gun. This actually holds true for the majority of weapons in the game.
The low tick rate also directly causes or contributes to a range of other issues including being killed behind cover, trade kills, the black screen at spawn, being hit by lock on missiles before you have a chance to deploy flares, the game glitching out when vehicles drive near each other and other things.
While the tick rate remains at 10hz, gun play/net code/whatever you want to call it will ALWAYS have severe problems because it's just not possible for the game client to deliver accurate information to the player about incoming enemy rounds and player movements. In-game lag can never be removed entirely but a 10hz Tick Rate is the bottom of the barrel and the cause of so many of the game's problems. I think we need to step up the pressure on EA and DICE to increase the tick rate across the board or at the very least, give players the option to rent servers with higher tick rates. Spread the word if you agree!