Luau Roblox Optimizer

Review checklist for scripts that live inside Roblox Studio. Every item names the symptom, the cause, and the one-line fix. Studio-only means: no external tooling, no file layout advice, no

--!strict

lectures. Script Analysis, the Output window, the Developer Console (F9), and MicroProfiler (Ctrl+F6) are the whole toolkit.

Review output

A review IS, in this order:

Exploits and data loss - anything a client can abuse or that drops saved data.
Crashes - nil indexes, races, errors that stop the script.
Leaks - connections, threads, and tables that outlive their owner.
Performance - work done more often than needed.
Animation and DataStore hygiene - the two areas below.

Each finding is one line:

line N - what breaks - fix

. Items that need the whole file to change (adopt a framework, restructure folders) are out of scope for a Studio review.

Scan triggers

Walk the file once. Each token below opens a fixed set of checks; report every check that fails, even when the same line already has a worse finding.

Seeing	Check
`Touched`	debounce, `hit` may be an Accessory handle, connection cleaned when the part goes
`OnServerEvent` , `OnServerInvoke`	arg types and ranges, cooldown, player data may not be loaded yet
`PlayerAdded`	load inside `pcall` , not-loaded flag, table entry cleared in `PlayerRemoving`
`CharacterAdded`	every connection, loop, and track has a `CharacterRemoving` or `Died` cleanup
`LoadAnimation`	called on an Animator, loaded once per character, has a matching `Stop`
`GetAsync` , `SetAsync`	`pcall` , retry, `BindToClose` , `UpdateAsync` for merges
`wait(` , `spawn(` , `delay(` , `while true`	`task.*` , an event instead of polling, an exit condition
`game.Players` , `game.Workspace` , any `game.X`	`game:GetService` cached at the top

1. Client/server mistakes

Symptom	Cause	Fix
Exploiters give themselves items or coins	Server reads an amount, id, or position from `OnServerEvent` args	Server computes the value itself; client sends intent only ( `"buyItem", itemId` )
Remote handler errors on odd input	No type or range check on args	`if typeof(amount) ~= "number" or amount < 1 or amount > MAX then return end`
Remote spam lags the server	No cooldown	Track `lastFire[player] = os.clock()` ; drop calls inside the cooldown
Script runs nowhere	LocalScript in ServerScriptService, or Script in StarterPlayerScripts	LocalScripts: StarterPlayerScripts, StarterCharacterScripts, StarterGui, StarterPack. Scripts: ServerScriptService, Workspace. ModuleScripts: ReplicatedStorage (shared) or ServerStorage (server only)
Client change doesn't show for others	Client edits Workspace directly	Client fires a RemoteEvent; server makes the change
Remote is nil on the client	Created by a Script after the LocalScript looked for it	Put RemoteEvents in ReplicatedStorage in the Explorer, not `Instance.new` at runtime, and `WaitForChild` on the client

2. Bugs that crash on respawn or leave

Symptom	Cause	Fix
`attempt to index nil` on `playerData[player]`	Remote or Touched fires before the async load in PlayerAdded finishes	Guard: `local data = playerData[player]; if not data then return end`
`attempt to perform arithmetic on nil` after leave	`PlayerRemoving` reads a table entry that never loaded	Same guard; never save when the load failed
Works in Play Solo, breaks in Team Test or live	Script assumes the character exists at start	`player.Character or player.CharacterAdded:Wait()`
Touched gives 2 to 5 pickups per coin	`Touched` fires once per limb	Debounce: `if coin:GetAttribute("Taken") then return end; coin:SetAttribute("Taken", true)` before awarding
Pickup ignores hats and tools	`hit.Parent` is the Accessory, not the character	`local char = hit:FindFirstAncestorOfClass("Model")` then `Players:GetPlayerFromCharacter(char)`
`Workspace.Folder.Part is not a valid member`	Dot chain runs before the part streams or loads	`WaitForChild` on the client; `FindFirstChild` plus a nil check on the server
Script errors once then goes silent	Error thrown inside a connection handler kills only that call, but an error at top level stops the whole script	Move setup into functions; wrap risky calls in `pcall`

3. Memory leaks

Symptom	Cause	Fix
Server memory climbs every respawn	`CharacterAdded` connects Heartbeat, Touched, or a `while true` loop and never stops it	Store the connection; disconnect in `CharacterRemoving` or `humanoid.Died` . Loops: `while character.Parent do`
Memory climbs per player who joined	Table keyed by `Player` never cleared	`playerData[player] = nil` in `PlayerRemoving`
Parts pile up invisibly	`part.Parent = nil` instead of `part:Destroy()`	`Destroy()` disconnects events and frees the instance
Tweens or tracks keep running on destroyed objects	Track or tween created per spawn, never stopped	Stop and destroy in `CharacterRemoving` , or keep one per character
Sounds and particles stack	`Instance.new` every event, never cleaned	Reuse one instance, or `Debris:AddItem(inst, seconds)`

Rule of thumb: every

Connect

task.spawn

while

Instance.new

, and

LoadAnimation

inside a

PlayerAdded

CharacterAdded

handler needs a matching cleanup in

PlayerRemoving

CharacterRemoving

4. Performance

Symptom	Cause	Fix
Everything slows under load	`wait()` , `spawn()` , `delay()`	`task.wait()` , `task.spawn()` , `task.delay()`
Script Performance window shows one script at the top	`FindFirstChild` , `GetChildren` , `GetDescendants` , or `game:GetService` inside Heartbeat or a tight loop	Cache references once above the loop
Polling loop per player	`while true do task.wait(0.1) if humanoid.MoveDirection ...`	Use the event: `humanoid.Running` , `humanoid.StateChanged` , `part:GetPropertyChangedSignal("Value")`
Heartbeat handler does work every frame	No throttle	Accumulate `dt` and run every 0.2 to 0.5s
String building lags	`s = s .. x` in a loop	Collect into a table, `table.concat`
Physics lag with static builds	Unanchored decorative parts	`Anchored = true` on anything that never moves
Low FPS on big maps	StreamingEnabled off	Turn it on in Workspace properties; guard client code for parts being nil
Unknown cause	Guessing	Ctrl+F6 MicroProfiler, Ctrl+P to pause a frame, find the wide bar. Wrap suspects in `debug.profilebegin("Name")` / `debug.profileend()`

5. Studio-specific anti-patterns

```
game.Players
```
,
```
game.ReplicatedStorage
```
as dot access. Works, but
```
game:GetService("Players")
```
is the documented path and survives renames. Cache it once at the top of the script.
```
Instance.new("Part", workspace)
```
. The parent argument replicates every later property change one at a time. Set properties first,
```
Parent
```
last.
A script inside a Workspace part that assumes
```
script.Parent
```
is ready. It is, but duplicated parts run duplicated scripts. Prefer one script in ServerScriptService that loops over a folder or a CollectionService tag.
Logic in a ScreenGui with
```
ResetOnSpawn = true
```
. The LocalScript restarts on every respawn and reconnects everything. Set
```
ResetOnSpawn = false
```
unless the UI must reset.
```
while wait() do
```
. Yields the whole script; use an event or
```
task.wait
```
.
```
print
```
in Heartbeat. The Output window itself becomes the bottleneck.
Testing DataStores in Play mode without Game Settings > Security > Enable Studio Access to API Services. Calls error with 403 and nothing saves.

6. Animation scripts

Symptom	Cause	Fix
Deprecation warning, animation may not replicate	`humanoid:LoadAnimation(anim)`	`humanoid:WaitForChild("Animator"):LoadAnimation(anim)`
Animation stacks or stutters	`LoadAnimation` called every time the action fires	Load once per character, store the track, reuse it
Animation never stops	Only `Play` is called	`track:Stop()` on the opposite event ( `Running` speed 0, tool unequipped, `Died` )
Walk overrides the attack	Wrong `Priority`	`track.Priority = Enum.AnimationPriority.Action`
Animation plays once and freezes	`Looped` unset for an idle	`track.Looped = true` for idles; leave false for one-shots
Works for you, invisible for others	Animation asset not owned by the game owner or group	Re-upload under the account or group that owns the place
Lag before the animation shows	Player animations loaded on the server	Load and play player-character animations in a LocalScript; the engine replicates them
Tracks pile up	Never destroyed	`track:Destroy()` in `CharacterRemoving` , or rely on one-per-character reuse

7. DataStore review

Symptom	Cause	Fix
Script errors with "Request was throttled" or HTTP 5xx	Bare `GetAsync` or `SetAsync`	Wrap every call in `pcall` ; retry up to 3 times with `task.wait(2 ^ attempt)`
Player data resets to default	Load failed, script fell back to defaults, then saved them	If the load pcall fails, mark the player as not loaded and skip the save
Coins lost on server shutdown	Only saving in `PlayerRemoving`	Add `game:BindToClose(function() for each player: save end)` ; in Studio this also runs when you stop Play
Two servers overwrite each other	`GetAsync` then `SetAsync`	`UpdateAsync(key, function(old) return new end)` for anything that merges
"DataStore request was added to queue" spam	Saving on every change	Save on `PlayerRemoving` , `BindToClose` , and at most every 60 to 120s
Old data unreadable after a schema change	Raw `UserId` as the key	String key with a version: `"v1_" .. player.UserId`
Nothing saves in Studio	API access off	Game Settings > Security > Enable Studio Access to API Services
Table saved as `nil`	Value contains an Instance, a function, or a mixed-key table	Save plain numbers, strings, booleans, and array or string-key tables only

Common mistakes in the review itself

Flagging
```
--!strict
```
, type annotations, or file structure. Studio devs cannot act on these without changing their workflow.
Suggesting a framework (Knit, ProfileService) as the first fix. Name the direct fix; mention a library only if the dev asks.
Listing twenty items with no order. Severity first, one fix each.

luau-roblox-optimizer

NPX Install

Tags

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