WYML [Fabric] Mod 1.16.5 is a server (and integrated server) performance mod. It carries out many tweaks relating to spawn and other important issues in the game.

What is WYML?
Another name of the mod is Why You Make Lag. It’s based on real-world matters that the author faced in their daily job.
It’s not a “fix-all lag for all” mod. Default configs will not only operate for everybody.
Basic features
Pause spawns if too many spawn attempts are unsuccessful in a chunk.
Slow down spawning when passing a specific limit of failed spawns in a chunk.
Cap mobs to a certain amount per chunk, with an intuitive config format for general end-users. There is another format an external GUI can appear by hosting providers.
Possible to disable DFU loading
Turn on forcing of garbage collection after the first world loading
Customize item despawn time
Rate limit entity pushing
Rate limit item stack merging checks
Combine item stacks into single TE to decrease item sticks on leaking device
Customize despawn distances and limits for each mob category
WYML is a server utility mod where you can switch off every option or edit them.
Requires
- Fabric Modloader
- Fabric API