Roblox's custom Lua runtime (Luau) introduces significant bytecode and VM architecture optimizations over standard Lua 5.1:

1. Fastcalls: Built-in functions (like , , ) bypass the standard function call overhead and execute directly as dedicated VM opcodes ().
2. Vector3 Native Type: Vector3 is a first-class tagged value (stored directly in the struct) rather than a heap-allocated userdata object.
3. Closure Environments: Luau separates C-closures and L-closures with strict capability bitmasks.

How do you analyze custom proto instructions and upvalue tables in IDA?

In Luau, the bytecode opcode table rotates between versions. Using an automated script to match the VM execution loop switch-cases against known opcode patterns makes decompilation much simpler.

The Vector3 inline optimization in Luau's union is really clever. Storing the 3 floats directly in the unused payload space saves millions of GC allocations per frame in physics loops.