WorldOptimiser
by Pelotrio
WorldOptimiser is a Forge mod that runs a world upgrade automatically when the set of installed mods has changed, so block IDs stay consistent.
What it does
When a world loads, WorldOptimiser hooks into Forge's mod loading events and compares the current mod list with the list saved in the world's NBT data. It reports the changes it detects, such as mods added, removed or updated to another version, and triggers Minecraft's built-in WorldUpgrader only when those changes make an upgrade necessary. Worlds with an unchanged mod list are left alone.
The mod was made to address block ID mismatches that appear in ReplayMod recordings after blocks, models or textures from mods are added or taken away. Before it existed, a player had to fetch the world, open it in singleplayer, optimize it manually and upload it again. WorldOptimiser replaces that process on dedicated and integrated servers alike. It runs on the server alone, so players need nothing extra to join.
Key features
Automatic detection
Mod additions, removals and version changes are monitored through ModMismatchEvent when the world starts.
Smart optimization
The world upgrade runs only when actual mod changes are detected, not on every launch.
ReplayMod block IDs
Changes to the block ID list that cause ReplayMod recordings to show incorrect blocks and textures are corrected during the upgrade.
Chat messages
Players see messages when the mod detects a change and when it performs the optimization.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Content creation servers
Servers that add or remove mods often, and whose players record replays, can keep recordings readable without manual world fixes.
Modpack updates
Updating a modpack that changes blocks, models or textures can be done without reprocessing the world by hand.
Who it’s for: Server owners who change their mod list while players record ReplayMod footage, and modpack maintainers who want block IDs to stay stable across updates.
Questions
Which loader does WorldOptimiser support?
Does a player need WorldOptimiser to join a server?
Does WorldOptimiser run on integrated servers?
Is the WorldOptimiser source code public?
In the catalog
WorldOptimiser is one of 3,545 Optimization mods on ModsFinder, and one of 1,441 Optimization mods for Forge. 11,154 mods support Minecraft 1.20.6.
More from Pelotrio
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What the author says
A Minecraft Forge mod that automatically optimizes worlds when mod changes are detected, specifically designed to solve ReplayMod block ID mismatch issues. This mod was created to solve a critical issue with ReforgedPlay Mod (version 0.3.1) where adding or removing mods that contain blocks, models, or textures causes…
Official listing
- Modrinth page
- modrinth.com/mod/worldoptimiser
- Owner
- Pelotrio
- Published
- 2025-09-17
- Updated on Modrinth
- 2025-09-17
- Facts verified
- 2026-10-15