#lag

spark records what your server spends its time on and gives you a link to a report. Use /spark tps, /spark health and /spark profiler to find the plugin, mod or entity behind your lag.

First work out which lag you have: low TPS (server), high ping (network) or low FPS (your PC). Then measure with spark and fix the real cause instead of hiding it.

A few safe changes to view distance, simulation distance, entity and item settings make a big difference. Change one thing at a time and measure with spark.

Generating new land is one of the heaviest jobs a server does. Use Chunky to generate the world ahead of time, then add a world border so players never trigger it during play.