Minecraft Realm Client Laggs in some Areas in the World

Hello Mojang/ Minecraft Team,

not long ago we purchased a Minecraft Realm. Now we have noticed that the players have laggs if they walk in certain areas. Only if they left this area it stops lagging. Would be great if you know how we can fix this without deleting this server.

with best regards

David

PS: Sry for my bad english i am from germany. =P