World Deletes items from inventory and reverts world chunks

Basically sometimes when I'm running around after playing for hours in a row and the world lags and a loading bar pops up, then the screen freezes and then it proceeds to delete new items in my inventory. once the world reaches a high amount of storage space on the system the world usually decides to do this, it usually decides to revert chunks to old saved versions (rarely) and it deletes items from my inventory (I smelted 15 stacks of sand and had it in my inventory and it removed it, checked the furnaces used and it wasn't there either) please fix A.S.A.P. as its ruining my survival world and will make me have to stick with having a world at like 5mb which is really tiny.