All Roads Lead to Rome

What it does

1. Unreachable target cache: when a mobs A* search exhausts its budget without getting anywhere, retries against that target are skipped for 10 seconds. Cached per mob.
2. Pathfinding throttle: at most 4 path computations start per server tick (configurable), which flattens spikes like the villager dawn rush
3. Search depth cap: A* is capped at 400 visited nodes. Failed searches are what burn CPU usage the most (800+ nodes), successful village scale paths rarely exceed 300
4. Recompute cooldown: after a failed pathfind, mobs wait 60 ticks before retrying instead of vanilla's 20
5. Reduced path recompute at distance: mobs 48+ blocks from every player refresh in progress paths at most every 60 ticks (3 seconds)
6. AI tick reduction at distance: mobs 48+ blocks from every player run their AI decisions every 4th tick, staggered across mobs: goal and target selectors for animals and monsters, and brains for idle or resting villager type mobs (compatible and recommended with Entity Culling).

Safety rules that apply everywhere:

• Mobs within 48 blocks of a player always behave exactly like vanilla
• Urgent mobs with an attack target or hurt in the last 10 seconds bypass everything and get full vanilla pathfinding
• Mobs in water or lava are never throttled, so they keep swimming and never drown
• Brains running anything other than idle/rest (working, panicking, or modded custom activities) always tick at full rate

Optionally you can install Configured to add in-game config options, most notably going below the recommended options won't most likely break the game (tested with mobs tick rate at 2, vanilla behavior stayed very similar, almost unnoticeable difference yet huge performance gain)

Compatibility

• Lithium optimizes different layers (it makes each A* node evaluation cheaper; ARLR reduces how often and how deep A* runs). They can be used together.
• The goal selector hook uses MixinExtras @WrapOperation, so other mods wrapping the same calls chain cleanly instead of conflicting.
• ARLR injects into PathNavigation.createPath, PathNavigation.recomputePath, Brain.tick, Mob.serverAiStep, and Level.setBlock.

Credits

This mod took heavy inspiration from Pathwright, a recent pathfinding optimization for Minecraft 26.1.2 mod.