OptimizeMod

Keep distant simulation quiet so active gameplay gets more CPU time.

OptimizeMod is a lightweight Fabric optimization mod for Minecraft 1.21.1. Its goal is simple: reduce work on entities and effects that players are not actively interacting with.

What OptimizeMod changes

1. Distance-based movement tick throttling (EntityTickMixin)

Hook: LivingEntity.tickMovement()

• Players are excluded.
• If no player is found within sleep distance (96 blocks by default), non-player living entities skip movement ticks (ENTITY_TICK_SKIP = 4 by default).
• If a player is present but farther than reduce distance (48 blocks), movement updates are throttled (roughly every other tick).

2. Distance-based AI throttling (MobEntityAIMixin)

Hook: LivingEntity.tickNewAi() (for MobEntity)

• If no player is found within reduce distance (48 blocks), AI updates are cancelled for that tick.
• In mid-distance ranges, AI updates are partially throttled (every other tick).
• While throttled/cancelled, despawnCounter is reset to avoid unwanted despawn side effects.

3. Particle throughput cap (ParticleManagerMixin, client)

Hook: ParticleManager.addParticle(...)

• Particle creation is capped with a local counter (MAX_PARTICLES_LIMIT = 4000).
• Excess particle spawn requests are dropped when the cap is exceeded.
• Intended to reduce client stutter from extreme particle bursts.

Important accuracy notes

• OptimizeMod does not guarantee fixed FPS/TPS/MSPT improvements.
• Real impact depends on mob density, player spread, chunk activity, modpack composition, JVM/runtime settings, and test scenario.
• Behavior changes for distant mobs/entities are intentional by design.

Reproducible evaluation (recommended)

To validate impact on your setup, compare baseline vs. OptimizeMod with identical conditions:

1. Same Java version, JVM args, mod list, seed, and config.
2. Same scenario and duration (recommended: 20-30 minutes per run).
3. At least 3 baseline runs + 3 OptimizeMod runs.
4. Collect comparable metrics:

• p50/p95 MSPT (spark or equivalent)
• CPU usage (process/system)
• FPS/frame-time (client tests)

5. Compare distributions (median/p95), not one-off spikes.

Installation

1. Install Fabric Loader for Minecraft 1.21.1
2. Install Fabric API
3. Place the OptimizeMod jar in mods/

Compatibility

• Designed to complement other optimization mods.
• As with any mixin-based mod, test your exact modpack before production deployment.