How Mob Caps Affect Minecraft Server Performance

Direct answer

Mob caps govern natural spawning opportunity; they are not a direct “FPS” slider. A lower cap can change survival gameplay and farm yields, so check population distribution before tuning.

How to check it

1. On Paper inspect /paper mobcaps for world-wide counts and /paper playermobcaps <player> for an individual player.
2. Compare players near farms, nearby caves and other dimensions. An apparently “slow farm” may simply compete with already-spawned mobs.
3. Record performance separately with spark. High mob caps can contribute to entity work, but the reported cap alone does not prove a tick bottleneck.

What to change

1. Check bukkit.yml spawn limits and world-specific config/paper-world-defaults.yml / world overrides instead of changing unrelated spigot settings.
2. Paper’s entities.spawning.per-player-mob-spawns affects whether limits are counted per player or server-wide. This is about distribution and should be tested with multiple players.
3. Adjust only the affected category and world after taking a backup of configuration. Avoid blanket reductions when the real cost comes from a farm retaining existing mobs.

Software and version notes

Verify the result

Repeat cap commands and confirm survival spawning, farms and average/peak MSPT remain acceptable with a realistic player distribution.

References

• PaperMC commands
• PaperMC world configuration
• PaperMC configuration overview