Missing items/ lag

Since I updated to 1.4.4 when im playing the game it will ocasionaly warp my back to wherever I was 30 seconds ago with all my work undone. The last time it did it I was trying to put items in a chest, when it stopped doing it the items where in the chest and I stopped warping but now that I went back to get the items they all dissapeared, they're not in my inventory either, the worst part is I lost alot of diamond and that's way to hard to find. Also I never had this problem in the previous version.