Deciding between roblox runservice heartbeat vs renderstepped usually comes down to whether you're trying to move a camera or just update some general game logic. If you've spent any time at all scripting in Luau, you've probably seen these events pop up in tutorials or documentation, and it's super easy to just pick one at random. But picking the wrong one can actually make your game feel jittery or, even worse, tank your players' frame rates.
Let's break down what's actually happening under the hood. Both of these are part of the RunService, which is basically the heartbeat of your game. It fires events every time the game loops. Since Roblox tries to run at 60 frames per second (or more, if a player has an unlocked frame rate), these events fire a lot. If you put a heavy script in either of these, you're going to notice it pretty quickly.
What is RenderStepped anyway?
First off, RenderStepped is a bit of a special case. It only exists on the client. If you try to use it in a regular Script on the server, it's just going to throw an error and refuse to work. This is because RenderStepped is tied directly to the rendering pipeline—the process that actually draws the pixels on your screen.
The thing about RenderStepped is that it fires before the frame is rendered. This makes it the "holy grail" for anything involving the camera. If you want a custom camera follow script or you're trying to make a weapon viewmodel look smooth, this is your best friend. Because it happens right before the draw call, any changes you make to the camera's CFrame will show up instantly in that frame.
But here is the catch: because it happens before the frame is drawn, the entire rendering process has to wait for your code to finish. If you've got a massive loop or some really inefficient math inside a RenderStepped connection, you're literally holding up the frame. The player's FPS will drop because the engine is waiting on your script before it can show the next image. That's why you should keep RenderStepped code extremely light.
Moving on to Heartbeat
Now, Heartbeat is a different beast entirely. It's much more chill. Unlike its counterpart, Heartbeat fires after the physics simulation has completed for that frame. It's available on both the client and the server, making it way more versatile for general gameplay programming.
Most of the time, if you're wondering which one to use, the answer is probably Heartbeat. Since it runs after the physics have been calculated, it's the perfect place for stuff like checking if a player is in a certain zone, updating a UI element that doesn't need frame-perfect precision, or moving non-physics objects.
One of the best things about Heartbeat is that it doesn't block the rendering of the frame in the same aggressive way RenderStepped does. While you still don't want to run a crypto miner in there, it's generally safer for your game's overall performance. If your Heartbeat logic takes a little too long, the frame has already been "prepared" in many ways, so the impact on visual smoothness is often less jarring than a stuttering RenderStepped script.
The Big Differences: A Closer Look
When we look at roblox runservice heartbeat vs renderstepped, the timing is the most important factor. Think of the game loop as a literal loop of events:
- RenderStepped fires (good for cameras).
- Input is processed.
- Physics are simulated.
- Heartbeat fires (good for logic and server stuff).
Because RenderStepped happens before physics, if you use it to move a part that has a Touch event, you might get some weird results because the physics engine hasn't "caught up" to where you moved the part yet. Conversely, if you use Heartbeat to update your camera, you might notice a slight "ghosting" or "jittery" effect. This happens because the camera is updating after the objects have already moved for that frame, so you're always seeing the camera one step behind the action. It's subtle, but players will feel it.
When should you use which?
I usually follow a simple rule of thumb. If the player is looking directly at it and it's tied to their input or the camera, use RenderStepped. For literally everything else, use Heartbeat.
Here are some quick examples to make it clearer:
- Custom Camera Systems: Use
RenderStepped. You want that camera to be locked to the player's movement without any delay. - Weapon Viewmodels: Use
RenderStepped. If the gun lags behind where the player is looking, it feels terrible. - Checking Player Distance: Use
Heartbeat. You don't need to know if a player is 5 studs away before the frame renders. After physics is totally fine. - Server-side NPCs: Use
Heartbeat. SinceRenderSteppeddoesn't exist on the server, this is your only option for high-frequency updates anyway. - Hovering Animations: If you have a coin spinning in the air,
Heartbeatis the way to go. It's a visual effect, but it doesn't need to be prioritized over everything else.
The "DeltaTime" factor
Whether you're using roblox runservice heartbeat vs renderstepped, you'll notice that both events pass a variable called step or deltaTime. This is the amount of time that has passed since the last frame.
I see a lot of newer scripters forget to use this. If you just do part.CFrame = part.CFrame * CFrame.new(0, 0, 1), your part will move faster on a computer running at 144 FPS than it will on a phone running at 30 FPS. That's because the event fires more often on the faster machine. To fix this, you multiply your movement by deltaTime. This ensures that your object moves at the same speed regardless of the frame rate. It's a small detail, but it makes your game feel professional and fair for everyone.
Why you might want to avoid RenderStepped
I know I said it's great for cameras, but I've seen people go overboard. Some devs put their entire character controller, animation logic, and UI updates into RenderStepped. This is a recipe for a laggy game.
The Roblox engine is actually pretty smart about how it handles tasks. If you throw everything into the render pipeline, you aren't giving the engine any room to breathe. If a player's computer is struggling, RenderStepped will keep forcing the engine to wait, making the lag even worse.
Actually, there's another event called Stepped (just to make things more confusing). Stepped happens before physics. It's useful if you're doing some crazy manual physics calculations, but for 99% of developers, the choice is really just between Heartbeat and RenderStepped.
Wrapping it up
To be honest, the best way to learn the difference is to try it yourself. Go into a baseplate, make a part follow the camera using Heartbeat, and then switch it to RenderStepped. You'll immediately see that the Heartbeat version feels "off"—almost like the part is vibrating or struggling to keep up.
But then, try running a heavy math calculation in RenderStepped and watch your frames drop. It's all about balance. Use RenderStepped sparingly for the stuff people see directly through the camera, and let Heartbeat handle the heavy lifting for the rest of your game logic. Once you get the hang of the timing, your scripts will be way more efficient, and your game will feel a lot smoother for your players.
It's one of those small technical hurdles that, once cleared, really opens up what you can do with visual effects and smooth gameplay in Roblox. Just remember: RenderStepped for the eyes, Heartbeat for the brains.