version: "1.0.1" name: roblox-performance description: "Use when profiling or fixing Roblox performance: low FPS, lag, memory, network load, slow phones, hot paths." when_to_use: "Also when the game stutters, phones overheat or crash, server heartbeat drops, before adding many parts/effects/UI, and when auditing performance before release." last_reviewed: 2026-10-02 sources:

• https://create.roblox.com/docs/en-us/performance-optimization/microprofiler
• https://create.roblox.com/docs/en-us/reference/engine/libraries/debug
• https://devforum.roblox.com/t/huge-memory-leak-prevention-for-everyone-or-most-people-atleast/3099605
• https://devforum.roblox.com/t/full-release-of-parallel-luau-v1/1836187
• https://luau.org/performance
• https://create.roblox.com/docs/reference/engine/classes/Actor
• https://create.roblox.com/docs/reference/engine/datatypes/SharedTable
• https://create.roblox.com/docs/scripting/multithreading

Roblox Performance

When to Load

Use for profiling and performance budgets. Pooling and lifecycle patterns: roblox-luau-patterns.

Quick Reference

Profiling Tools

• MicroProfiler (Ctrl+F6): Frame breakdown of scripts, physics, rendering.
• Developer Console (F9): Memory, network, rendering, and server stats.
• Script Profiler (Ctrl+Alt+F5): Per-script CPU and heap.
• Labels: debug.profilebegin/debug.profileend mark regions; debug.setmemorycategory labels memory. Gate instrumentation behind a flag.

Performance Targets

Optimize measured hot paths, not folklore. Throttle from measurements; re-profile after shipping.

Parallel Luau

• Use Actors only after profiling identifies isolatable CPU work.
• Workers compute; synchronize before restricted DataModel writes.
• Do not rely on shared module state across Actors. SendMessage copies data; SharedTable supports shared state and atomic updates.

Hot-loop cost model

• Luau optimizes global imports; avoid folklore function hoisting/unrolling. Environment impurity can disable optimizations. Profile allocations as well as CPU; GC cost may occur later.

Object Pooling

Pre-clone and reuse. Canonical pool code (token-lease ownership): roblox-luau-patterns.

StreamingEnabled Essentials

• On by default. Container-scoped: only Workspace descendants stream. ModelStreamingBehavior = Improved streams non-BasePart descendants with their parent Model; Legacy streams only BaseParts.
• Streamed-out = parented to nil, not destroyed. Luau refs persist if it streams back.
• Config (Studio): target defaults 1024, min 64; set StreamingIntegrityMode; tune from data.
• Gotcha: FindFirstChild("DistantPart") returns nil if streamed out. Use WaitForChild with timeout.

Mobile

• Profile geometry, textures, particles, UI, shadows on low-end devices.

Full reference with code examples and API tables: references/full.md