Diagnose Java server lag

Last updated: July 23, 2026

This guide shows you how to identify server-side, connection, or client lag and profile a NolimitHost Minecraft Java Edition server with spark.

First identify where the lag occurs. Server-side, connection, and client lag require different fixes.

Lag type	Common signs
Server-side	The world slows for everyone, mobs freeze, or mined blocks reappear.
Connection	One or more players have delayed actions or rubber-band while moving.
Client	One player's display stutters or loses frames while the server continues normally.

Check server-side causes

Open the Console in the NolimitHost Game Panel (log in at https://panel.nolimithost.cc/ and select your server first) and read it for repeated errors, watchdog warnings, or overloaded messages.
Check whether the problem began after adding a plugin, mod, add-on, farm, redstone machine, or large group of entities.
In the Game Panel's File Manager, open server.properties (the main server configuration file) and review view-distance, simulation-distance, and entity-broadcast-range-percentage. If you change these values, stop the server first and restart it after saving, so the running server does not overwrite your edits.
Test one change at a time and compare performance under similar player load.

Use spark on compatible plugin server software to find expensive plugins, tasks, entities, and server threads.

Install spark — Upload a compatible spark .jar to the /plugins folder in the Game Panel's File Manager (on plugin-based servers), then restart the server.
Start a profiler — Open the Console in the Game Panel and run the profiler during the lag you want to investigate.
```
spark profiler start
```
Stop and open the report — Let it collect representative activity, then stop it.
```
spark profiler stop
```
Open the generated report link.
Read the result — Check TPS (ticks per second, how fast the server updates the world; a healthy server runs at 20), milliseconds per tick, memory and garbage collection, then inspect the plugin, mod, world, or thread consuming the most processing time.

Warning: A spark report may contain server details. Review it before sharing the link publicly.