Find What's Causing Server Lag

Start a CPU Profiling Session

When your server is running slowly, use Spark's profiler to identify which plugins or game systems are consuming the most CPU time.

1. Run /spark profiler start to begin recording

2. Let the server run normally for 30–60 seconds while you reproduce the lag (e.g., load chunks, run redstone, spawn mobs)

3. Run /spark profiler stop to end the session

4. Spark generates a link to an interactive web report

Read the Report

The report shows a call graph—a tree of which functions called which other functions, ranked by CPU time spent. Look for:

• Plugin names at the top of the tree (if a plugin dominates, it's the culprit)
• Game systems like Chunk.tick or Entity.tick (indicates world load or mob issues)
• Percentages next to each entry (shows how much CPU that function used)

If a specific plugin appears repeatedly, consider disabling it, updating it, or adjusting its config. If it's a game system, you may need to reduce entity count, chunk load distance, or redstone complexity.