I've recently started up a hardcore world with no mods installed on it apart from optifine. Ever since I created the world I have experienced heavy framerate drops when loading new chunks that have never been loaded before. I have tried backing up the world and loading the backup and tried optimising the world so that it doesn't work on previous versions, both of which have had no affect what so ever on he framerate. These drops end up going down to about 20fps and periodic freezing whereas if I walk around in or close to chunks that have been previously been loaded multiple times before I can get around 60fps. I have not tried allocating more memory to it. I do not know what to do about it and would like to find a solution on something that works.