That is one possible cause, but a server can also fall behind when a plugin hogs CPU resources or many CPU-intensive events are triggered at once, such as many large explosions going off or pistons firing.This message is written when the server is unable to update the world in normal speed (20 frames per second). This is mainly due to saving and loading chunks. We're working on it..
If you're running plugins, the most likely culprit is a plugin. Minecraft is single-threaded and most plugins are also single-threaded, so when a plugin takes too long in its processing, the entire server loop is delayed. Try disabling your plugins one-by-one until the messages disappear; then, reconfigure, update, or remove the plugin that was causing the issue. Common culprits include:
* Mapping plugins
If the issue happens even with all plugins disabled, something's amiss with Minecraft itself and how it is processing your world. As mentioned previously, it could be an issue with pistons or explosions, the world might be corrupted, or it is possible that the game isn't handling the movement of certain mobs correctly. Please contact us and have us run a repair, which will run Chunkster on your world to look for corruption.