Despawning System
There are two parts to the Despawning System. Both parts are meant to reduce Mob count and manage lag.
The first part is simple; it just makes it so no Spore Mobs will spawn if there aren't players in the world. This is meant for servers.
The second part is more complex, but essentially each tier of Spore Mob has a maximum number of individuals from that tier that can exist in the world. Every minute, the Despawning System will count the Mobs in the world based on the Mob tier. If there are too many Mobs from any tier, the system will despawn the ones farthest away from a player. The following is a list of Mob tiers and their maximum number of individuals:
Evolved - 35
Hyper Evolved - 20
Organoids - 40
Scents - 30
Projectiles - 100 (not listed in Config)
Some mobs are specifically ignored by the Despawning System via a changeable list found in the Config. Scampers, Gastgebers, Specters, Reapers, Vanguards, Infested Constructs, Wombs, Proto Hiveminds, and Hivetumors are all ignored by the Despawning System.
Note the 30 Scent limit is different from the Local Scent Cap.
Organoids also have their own custom method of despawning to prevent lag and overcrowding, explained on the Organoids page.
Mob Cap
Separate from the Despawning System, there exists a basic Mob cap that makes it so only 40 Mobs (Infected, Conductors, Chemists, Inebriaters, and Experiments by default unless changed in the Config) can spawn naturally (meaning in dark areas or within Structures).