How to Find the Mods Causing Vintage Story Server Lag

Waiting for every block drop takes the fun out of a mining trip. Capture the slowdown, reproduce it on a separate server copy, then test smaller mod batches. Keep your friends' live world out of the experiment.

Catch the slowdown before changing mods

Low FPS points towards a client problem; delayed block drops and frozen creatures are documented server-lag symptoms. Check whether the whole group feels it. If only one friend struggles, check their connection too.

On supported CreeperHost servers, WAILT shows live tick rate and entity timings by type and chunk, helping you locate busy areas. On Premium and Pro, Ask Theo can check recent logs, installed mods and the selected world to help choose your next check. You approve any supported changes.

Note the time, players, location and activity. As the server owner, enter this in chat:

/debug logticks 100

This debug command records a breakdown of ticks—server simulation updates—taking longer than 100 milliseconds. Reproduce the lag, then repeat the command to stop logging. Save server-main.txt from Logs inside the server's active data folder.

Version note: The performance guide above was last verified for version 1.15. Check your installed version's command help if behaviour differs. A quiet capture at 100 ms isn't an all-clear.

Use matching timestamps to choose suspects. Neither a busy chunk nor a mod name in an error proves that a mod caused the lag.

Protect your world with an isolated copy

Stop the live server cleanly and wait for shutdown to finish. Back up its entire active data folder, plus any saves, mods or mod data stored elsewhere. Keep this backup untouched.

CreeperPanel's Worlds controls let you download a save and upload it to a separate Vintage Story test service. Copy mods and settings too; changing the live service's active world doesn't isolate them.

Build a separate dedicated server with matching game and mod versions and settings. Give it its own data folder, using a separate dataPath for standalone hosting. Check that SaveFileLocation and ModPaths in serverconfig.json point to test files, never live data.

Keep an untouched copy of this isolated setup as your baseline. Removing content mods can leave blocks or items replaced or unknown, so restore that baseline before every run.

Disable batches and compare the results

Check each mod's side and dependencies—the other mods it needs. Start with server-side and universal mods. Keep required libraries enabled for the remaining mods, and match any client requirements.

Stop the test server before restoring files or changing mods, then restart it. Choose the route that fits your setup:

• CreeperHost: Open Vintage Story → Mods on the separate test service. Use the mod manager to see installed mods and enable or disable the test batch without moving files.
• Manual hosting: Move the batch's added mod files outside every folder listed in ModPaths. Leave the built-in game mods in place.

Follow the game's split-test approach. Keep the test hardware, players, location and activity consistent. Capture logs for each run, using the same duration, long enough to catch the original slowdown.

1. Reproduce the lag with the full mod set. If the test copy runs smoothly, improve the reproduction before removing anything.
2. Disable roughly half your added mods. Keep dependencies intact, restart and repeat the activity.
3. Narrow the suspect batch. If removing it helps, halve that batch for the next test. Otherwise, restore it and test the remaining mods. Start each run from your untouched baseline.
4. Confirm the suspect. Repeat full-set versus suspect-disabled comparisons from fresh baselines. Check that the slowdown reliably follows the change.

If the results don't add up

• The server won't start: Restore missing dependencies or the previous mod set. A failed launch isn't a successful performance test.
• Both halves run well separately: An interaction or combined workload may be involved. Test combinations around the original trigger rather than declaring one mod broken.
• Only exploration lags: Restore the pre-exploration baseline and follow the same route into ungenerated terrain. Revisiting existing terrain doesn't repeat the same generation work.

If removing mods doesn't reliably help, investigate the workload or connection rather than naming a culprit.

Apply the fix with a way back

Check the mod author's compatibility and removal advice. CreeperPanel's available updates match the installed game version, but still test the update with your mod set. Try updates or configuration changes on a fresh copy first.

Make the live change during maintenance, after taking a fresh backup. If it fails, stop the server and restore that backup with matching mods and settings.

On Premium and Pro, SaveGuard offers recovery points with a file-change preview and backs up the current world before restoring. Choose from the points shown for your service and check which files are covered. Keep your independent baseline, and never overwrite newer live progress with an experimental save.

Need a hand on CreeperHost? Send our support team your logs, version list and steps that reproduce the lag.