Tired of waiting minutes every time you boot up large Minecraft 1.12.2 modpacks like RLCraft, MeatballCraft, or GreedyCraft?

Startup Flow is a dual-purpose optimization mod designed specifically to eliminate startup lag on both CleanroomMC and standard Minecraft Forge 1.12.2. It tackles two of the heaviest launch bottlenecks:

1. Caching FermiumBooter's Startup Scan: Bypasses the repetitive, disk-heavy ClassGraph scanning of hundreds of mod JAR files on every boot by caching the results to disk.
2. Multi-Threaded Model Baking: Parallelizes block and item model compilation across multiple worker threads instead of forcing everything through a single CPU core.

• Instant Replay of Jar Scans: On warm boots, Startup Flow pre-loads cached mod IDs and @MixinConfig toggles into FermiumBooter in just ~24 milliseconds, completely skipping the expensive disk scan.
• Multi-Core Model Baking: Automatically detects your CPU cores and bakes block/item models concurrently, dramatically speeding up client loading on packs with tens of thousands of model variants.
• Smart Invalidation Fingerprint: Automatically detects changes in your mods/ directory (including nested folders like mods/1.12.2/) as well as config/fermiumbooter.cfg content changes. The cache updates itself only when your mod setup actually changes.
• Universal Compatibility: Works natively on both Cleanroom and standard Forge instances.
• Client & Server Friendly: Caching benefits both client launches and dedicated servers. Model baking optimizations safely stand by on headless servers.
• Safe & Non-Intrusive: Uses reflection with zero compile-time dependencies on FermiumBooter. If FermiumBooter is absent, Startup Flow steps aside gracefully without logging scary errors.
• Built-in OptiFine & VintageFix Protection: Automatically detects OptiFine and disables conflicting texture mixins to preserve custom shaders and textures. Fully compatible with VintageFix's dynamic resources.

Measured on a real-world modpack with 234 mods and 564 @MixinConfig toggles (Cleanroom 0.6.13-alpha, identical hardware):

Correctness Guarantee: 0 Mixin errors, 0 crashes, and identical toggle evaluation verified between cold and warm boots.

• CleanroomMC: Fully supported and recommended.
• Minecraft Forge 1.12.2: Fully supported on Forge 14.23.5.2847 or higher.
• FermiumBooter: Supported automatically. The scan cache activates when FermiumBooter is installed.
• OptiFine: Fully compatible. Startup Flow detects OptiFine at runtime and dynamically disables its texture atlas mixin so OptiFine's shader and texture pipelines remain 100% untouched.
• VintageFix: Fully compatible. If VintageFix has dynamic_resources enabled (loading models on-demand), Startup Flow's model baker safely idles while the FermiumBooter scan cache continues speeding up startup.
• Surge / CensoredASM: Fully compatible with no conflicting transformations.

• Minecraft 1.12.2
• Minecraft Forge (14.23.5.2847+) OR Cleanroom (0.6.x+)
• MixinBooter (10.0 or newer)
• Optional: FermiumBooter (required only if you want scan caching)
• Java 8 up to Java 25

1. Ensure MixinBooter is present in your mods folder.
2. Download startupflow-1.0.1.jar and place it into your mods folder.
3. Launch the game. The first boot records the cache; every launch thereafter will automatically benefit from warm boots!

Configuration file: config/startupflow.cfg

"Model Baking" {
    # Bake block and item models across multiple worker threads instead of a single thread.
    B:"Enable Parallel Model Baking"=true

# Number of threads for model baking (0 = auto-detect CPU cores).
I:"Model Baking Threads"=0

# Compute texture atlas mipmap levels concurrently across multiple threads.
B:"Enable Parallel Mipmaps"=true

# Number of threads for mipmap generation (0 = auto-detect CPU cores).
I:"Mipmap Threads"=0

}

• Disable Cache via JVM flag: Add -Dfermiumscancache.disable=true to your launcher arguments.
• Disable Cache via File Marker: Place an empty file at config/fermiumscancache.disabled.
• Force Rescan: Delete config/fermiumscancache.json.

• /startupflow status — View current model baking threads and status.
• /startupflow toggle — Toggle parallel model baking on or off.

Startup Flow is open-source software licensed under the GNU General Public License v3.0 (GPL-3.0). Source code is available on GitHub.