While it’s interesting that your benchmarks show a slight improvement, there are a few technical reasons why using task.desynchronize() for a single variable assignment is generally considered counter-productive in Roblox development.
Here is a breakdown of why you are seeing those numbers and why this pattern might actually hurt performance in a real game environment.
1. The Overhead of Context Switching
task.desynchronize() and task.synchronize() are not “free.”
- Desynchronize: The engine must pause the execution of your script, package the current state, and move it to a worker thread.
- Synchronize: The engine must wait for the “Parallel Phase” of the frame to finish, then move your script back to the “Serial Phase” (Main Thread) to execute
MoveTo.
The time it takes to move between threads is often significantly longer than the time it takes to fetch the LocalPlayer.Character. By doing this, you are asking the CPU to do more “management” work to save a “micro-operation.”
2. The “MoveTo” Bottleneck
The most expensive part of your code is V:MoveTo(). Because MoveTo changes the physics state of the world, it cannot run in parallel.
In your second snippet, you:
- Switch to a worker thread.
- Get a reference to the character (extremely fast).
- Wait for the engine to sync back to the main thread.
- Run the heavy
MoveTo operation.
The slight “gain” you see in your testing is likely a measurement artifact. When you desynchronize, the script’s execution is split across different phases of the frame. Your profiler might be recording the time spent in the Serial phase only, ignoring the time the script spent “waiting” in the parallel pool.
3. Parallel Luau’s “Sweet Spot”
Parallel Luau is designed for heavy computation. To see real benefits, you generally need to be doing something that takes a lot of CPU cycles, such as:
- Pathfinding calculations for 100+ NPCs.
- Complex math (Fractals, procedural terrain generation).
- Raycasting hundreds of times per frame.
Using it to fetch a variable is like driving a semi-truck to the mailbox at the end of your driveway; the startup time of the engine takes longer than just walking there.
4. Why your testing might show it’s “faster”
If you are using os.clock() or the MicroProfiler to measure this, the desynced version might appear faster because you are essentially deferring work.
- In Snippet 1, the script runs start-to-finish in one go.
- In Snippet 2, the script runs a tiny bit, “yields” to the parallel phase, and finishes later.
The “Total Frame Time” (the most important metric for FPS) will almost certainly be higher in Snippet 2 because of the synchronization overhead.
Recommendation
If you want to optimize this specific code:
- Cache the Character: Don’t look up
game.Players.LocalPlayer.Character every heartbeat. Define it once outside the connection and update it only when CharacterAdded fires.
- Use CFrame/PivotTo:
MoveTo is an old method that performs extra checks (like making sure the character doesn’t get stuck in the floor). Using V:PivotTo() or setting V.PrimaryPart.CFrame is generally faster and more predictable.
Optimized Version:
local player = game.Players.LocalPlayer
local char = player.Character or player.CharacterAdded:Wait()
player.CharacterAdded:Connect(function(newChar)
char = newChar
end)
game["Run Service"].Heartbeat:Connect(function()
if char and char.PrimaryPart then
char:PivotTo(CFrame.new(0, 0, 0))
end
end)
This will likely outperform the desynchronized version without the thread-switching overhead!
