ModernSaveInstance

Fork of UniversalSynSaveInstance with decompilation prepass & optimizations.

Created by Sashenka — Discord

Files

File	Description
saveinstance.luau	Core saveinstance engine (serializer + options)
prepass.luau	Decompilation prepass + auto-loads saveinstance

Usage

Basic (saveinstance only)

local s = loadstring(game:HttpGet("https://raw.githubusercontent.com/achmdfzn/ModernSaveInstance/main/saveinstance.luau"))()
s({ SafeMode = true })

With PrePass (recommended)

PrePass caches decompiled scripts first, then loads saveinstance — avoids timeout on large games.

local p = loadstring(game:HttpGet("https://raw.githubusercontent.com/achmdfzn/ModernSaveInstance/main/prepass.luau"))()
p({ SafeMode = true })

PrePass only (skip saveinstance)

local p = loadstring(game:HttpGet("https://raw.githubusercontent.com/achmdfzn/ModernSaveInstance/main/prepass.luau"))()
p(nil, { SkipSaveInstance = true })

PrePass options

Option	Type	Default	Description
SkipPrepass	bool	false	Skip decompilation prefetch
SkipSaveInstance	bool	false	Skip loading saveinstance after prepass
RequestsPerMinute	number	1400	Decompile API rate limit
MaxInFlight	number	30	Parallel decompile requests
RequestTimeout	number	20	Per-request timeout (seconds)
ApiUrl	string	https://api.lua.expert/decompile	Decompilation API endpoint
UssiRepoURL	string	(this repo)	Where to fetch saveinstance.luau
UssiScript	string	saveinstance	Script name (.luau appended)
Verbose	bool	true	Log progress to console

saveinstance Options

All USSI options are supported, including:

• SafeMode — Most stable mode (recommended for beginners)
• DecompileTimeout / BytecodeTimeout — Timeout guards
• IgnoreSharedStrings — Skip SharedString processing
• TreatUnionsAsParts — Convert UnionOperations to Parts (Solara auto-enabled)
• IsModel — Save as .rbxmx instead of .rbxlx
• FilePath — Custom output path (auto-appends extension)
• ExtraInstances — Save additional non-game instances

Full list: see --- @field declarations in saveinstance.luau or the USSI docs.

Optimizations

• Iterative stack machine — replaces recursive tree walk, no stack overflow on deep hierarchies
• Appendfile direct write — writes XML incrementally instead of accumulating in memory
• GetInheritedProps chain-of-arrays — faster property inheritance lookup via table.move
• Auto-update — checks VERSION file on GitHub at load
• Weak referents table — prevents memory leaks