Bad lag in my world only (only beta)

Hey mojang so i logged in the game and get in world then this lag return only at my world.but I was just mining diamonds and ores then an extremely lag comes and I get out the cave I was mining and the lag doesn't stop.so I quit the game and logged in again if its fixed but the same thing . mojang try to fix this lag in my world.
World seed-21453705).only on beta.