honestly bro i believe its just the servers because when you join in your constantly downloading information from the host of the server such as zombie movements, your health,kill count, etc. but it could also be your hard drive because Arma more specifically Day Z is very demanding when it comes to your transfer rate if you could post your specs and your internet speed i can give you a better answer but i currently do not have enough information to give you a 100% accurate answer to your problem also i have drops in frame rates sometimes and i have a beast of a computer its a alienware so yea but um please post more info about your pc