Roblox Performance Optimization

Quick Reference

Technique	Impact	When to Use
StreamingEnabled	High	Large open worlds
Object pooling	High	Frequent spawn/destroy
Cache references outside loops	High	Heartbeat/RenderStepped
task.wait() over wait()	Medium	All scripts
MeshParts over Unions	Medium	Many unique shapes
LOD (hide at distance)	Medium	Complex models
Anchor static parts	Medium	Reduce physics budget
Limit PointLights	High	Any scene with many lights

---

StreamingEnabled

Enable for large worlds — engine sends only nearby parts to the client.

-- Studio: Workspace > StreamingEnabled = true
workspace.StreamingEnabled = true
workspace.StreamingMinRadius = 64
workspace.StreamingTargetRadius = 128

• Parts outside the radius are nil on the client — always guard with if part then.
• Set Model.LevelOfDetail = Disabled on models that must always be present.
• Pre-stream an area before a cutscene or teleport:

workspace:RequestStreamAroundAsync(targetPosition, 5) -- 5s timeout

---

Hot-Path Loop Optimization

RunService.Heartbeat and RenderStepped fire every frame (~60×/sec). Keep them lean.

Bad — searching the hierarchy every frame

RunService.Heartbeat:Connect(function()
    local char = workspace:FindFirstChild(player.Name)
    local humanoid = char and char:FindFirstChild("Humanoid")
    if humanoid then humanoid.WalkSpeed = 16 end
end)

Good — cache references once, do work only when needed

local humanoid = nil

Players.LocalPlayer.CharacterAdded:Connect(function(char)
    humanoid = char:WaitForChild("Humanoid")
end)

RunService.Heartbeat:Connect(function(dt)
    if not humanoid then return end
    humanoid.WalkSpeed = 16  -- cached reference, no search
end)

Rules:

• Cache game:GetService() and part references outside the loop.
• Never call FindFirstChild, GetChildren, or GetDescendants inside Heartbeat.
• Throttle work that doesn't need every frame:

local TICK_INTERVAL = 0.5
local elapsed = 0

RunService.Heartbeat:Connect(function(dt)
    elapsed += dt
    if elapsed < TICK_INTERVAL then return end
    elapsed = 0
    -- expensive work here, runs 2×/sec instead of 60×/sec
end)

---

task Library vs Legacy Scheduler

Always use task — wait() and spawn() throttle under load and are deprecated.

Legacy	Modern
wait(n)	task.wait(n)
spawn(fn)	task.spawn(fn)
delay(n, fn)	task.delay(n, fn)
coroutine.wrap(fn)()	task.spawn(fn)

---

Object Pooling

Reuse instances instead of creating and destroying them every frame.

-- ObjectPool ModuleScript
local ObjectPool = {}
ObjectPool.__index = ObjectPool

function ObjectPool.new(template, initialSize)
    local self = setmetatable({ _template = template, _available = {} }, ObjectPool)
    for i = 1, initialSize do
        local obj = template:Clone()
        obj.Parent = nil
        table.insert(self._available, obj)
    end
    return self
end

function ObjectPool:Get(parent)
    local obj = table.remove(self._available) or self._template:Clone()
    obj.Parent = parent
    return obj
end

function ObjectPool:Return(obj)
    obj.Parent = nil
    table.insert(self._available, obj)
end

return ObjectPool

-- Usage
local pool = ObjectPool.new(ReplicatedStorage.Bullet, 20)

local function fireBullet(origin)
    local bullet = pool:Get(workspace)
    bullet.CFrame = CFrame.new(origin)
    task.delay(3, function() pool:Return(bullet) end)
end

---

Level of Detail (LOD)

Built-in: Set Model.LevelOfDetail = Automatic — engine merges distant parts into an imposter mesh automatically.

Manual distance-based LOD:

-- LocalScript
local INTERVAL = 0.2
local LOD_DISTANCE = 150
local elapsed = 0

RunService.Heartbeat:Connect(function(dt)
    elapsed += dt
    if elapsed < INTERVAL then return end
    elapsed = 0

    local dist = (workspace.CurrentCamera.CFrame.Position - model.PrimaryPart.Position).Magnitude
    local visible = dist < LOD_DISTANCE
    for _, v in model:GetDescendants() do
        if v:IsA("BasePart") then
            v.LocalTransparencyModifier = visible and 0 or 1
        end
    end
end)

---

Reducing Draw Calls

• Merge parts that share a material into one MeshPart (export from Blender as .fbx).
• MeshParts batch better than CSG Unions (Unions re-triangulate at runtime).
• Reuse materials — 10 parts sharing SmoothPlastic costs far less than 10 unique textures.
• Use TextureId on a single MeshPart instead of stacking Decals on many parts.

---

Profiling with MicroProfiler

1. Press Ctrl+F6 in-game to open MicroProfiler.
2. Press Ctrl+P to pause and inspect a single frame.
3. Look for wide bars in heartbeatSignal (Lua), physicsStepped (physics), or render (GPU).
4. Label your own code:

RunService.Heartbeat:Connect(function()
    debug.profilebegin("MySystem")
    -- your code
    debug.profileend()
end)

---

Common FPS Killers

Cause	Fix
Thousands of individual parts	Merge into MeshParts
Unanchored static geometry	Anchored = true on anything that never moves
Many PointLight / SpotLight instances	Limit to ~10–20 dynamic lights per area
High-rate ParticleEmitters	Lower Rate and Lifetime; disable when off-screen
wait() under heavy load	Replace with task.wait()
FindFirstChild chains inside Heartbeat	Cache on load
StreamingEnabled off on large maps	Enable it
Model.LevelOfDetail = Disabled everywhere	Use Automatic where safe

---

Common Mistakes

Mistake	Fix
workspace:FindFirstChild every frame	Cache reference on character/model load
Destroying and re-creating bullets/effects	Use an object pool
wait() in tight loops	task.wait()
All parts with unique materials	Standardize to a small set of shared materials
ParticleEmitters enabled off-screen	Disable Enabled when particle source is not visible
Physics on decorative parts	Anchored = true