Free Server Saver

Free Server Saver

Lag reducer for low-RAM Minecraft servers (Falixnodes, Minehut, self-hosted) — anything stuck on 2-4 GB of RAM.

The problem

If you've seen any of these on your server, it's the same root cause:

• Mobs teleporting 5-10 blocks instead of moving smoothly
• You and a friend get disconnected even though only 2 people are online
• The server freezes for half a second every few minutes
• "Server crashed because it ran out of memory" after a fine hour of play
• "OutOfMemoryError: Metaspace" even though RAM Boost is active

All of those are GARBAGE COLLECTION PAUSES. Your host gives you a small heap, modpacks fill it, the JVM stops the world to clean up. To players, that looks identical to network lag.

The fix

Free Server Saver polls heap pressure every 2 seconds and gradually scales back AI ticks, mob spawns, view distance, and chunk loads BEFORE the heap fills. No GC pause, no rubber-banding, no disconnects.

How it works — 5 tiers, hysteresis on recovery

• BELOW 60% heap — NORMAL — vanilla behavior
• 60-70% — L1 — far mobs tick every other tick; 50% of natural spawns rejected
• 70-80% — L2 — distant mobs at 1/8 tick rate; all natural spawns rejected
• 80-85% — L3 — view distance compressed to 6 chunks
• 85%+ — L4 EMERGENCY — distant mobs force-discarded; server tick rate halved

When the heap recovers, every change reverses automatically.

Protections — what stays normal even at L4

• Bosses (EnderDragon, Wither, Warden, Elder Guardian, Ravager, Hoglin, or anything with >80 max HP)
• Villagers, wandering traders, golems, allays — your iron farm and trading hall keep working
• Named, leashed, tamed, persistent mobs
• Combat-engaged mobs — keep ticking at full rate
• Newly spawned (< 10s) mobs — grace period
• Crops, leaves, snow, fire — random ticks are NEVER touched (Lithium handles those better)

Also addresses

• 4 GB world cap (free-host hard ceiling) — /fss storage to watch, /fss prune to identify pruneable chunks
• 10-minute startup limit — boot-time history + early warning
• Metaspace OOM — RAM Boost extends heap, not Metaspace. We monitor it separately
• Chunk-generation lag — /fss pregen <radius> for spawn-area pre-gen
• Mob-farm detection — opt-in scan that flags chunks with 30+ same-type mobs
• Stuck-entity crashes — entities / block-entities that throw the same tick exception repeatedly are auto-quarantined before they crash an unattended server (yields entirely to Neruina / Bug Fix Mod / Failsafe if installed; bosses are never discarded)

Plays well with everything

Free Server Saver detects competing performance mods and yields rather than fighting them. Install side-by-side with:

• Lithium, FerriteCore, ModernFix — these handle static optimization; we handle adaptive
• Adaptive Performance Tweaks, Tick Dynamic, Tick Tweaks — we yield to their tick-time logic
• Where's my Brain, DAB, OptimizeMod, Immersive Optimization, No See No Tick — we yield to their distance throttle
• Chunky — we yield our pregen command to its better one

The startup log shows which modules yielded and why. No double-throttling, no /tick rate fights, no surprises.

Commands

All under /fss (or the full alias /freeserversaver), op-only (permission level 2):

• help — all subcommands with descriptions
• status — current tier + heap percentage
• metrics — heap, tier, players, chunks, view distance
• history — last 20 tier transitions, color-coded
• env — JVM heap/CPU snapshot from server start, with RAM Boost detection
• lagspikes — recent 100ms+ ticks with heap state at the time
• top entities — top 10 entity types by count
• inspect chunks — per-dimension loaded / forced / player counts
• tuning — current AutoTuner threshold offset
• prune — identify unreachable loaded chunks (flood-fill)
• storage — world directory size vs the host's 4 GB cap
• pregen <radius> — pre-generate chunks around you
• quarantine — recently quarantined entities / block-entities

Languages

Output translated to 9 languages: English, 日本語, Deutsch, Português (BR), Español, 简体中文, 한국어, Français, Русский. A Japanese client sees Japanese on a server in any locale.

Translations are machine-generated as a starting point. Native-speaker corrections are very welcome — open a PR or issue on GitHub.

What it does NOT do

• Network ping issues — geographical, no mod can help
• Bypass the host's idle-shutdown timer with fake players — that's what many free hosts ban (Carpet). Free Server Saver works within the host's rules

Requirements

• Minecraft 1.21.1
• NeoForge
• JDK 21

(1.21.2+ port pending — vanilla's random tick logic changed in 1.21.2 and we want to validate first.)

Companion mods (strongly recommended)

For a complete low-RAM stack, install alongside:

• Lithium — allocation-cheap optimizations across the engine
• FerriteCore — 40-50% block-state memory reduction
• ModernFix — mod-loading speedup; helps with that 10-minute free-host boot limit

Free Server Saver intentionally stays out of their lane. They handle static optimization, we handle adaptive response.

License & attribution

All Rights Reserved (free to put in any modpack, no permission or credit needed). See NOTICE.md in the GitHub repo for full attribution.

UNOFFICIAL community mod. Not affiliated with any hosting provider.