Getting your game to feel fluid usually boils down to how well you handle roblox runservice. If you've ever noticed a part stuttering as it moves or a camera that feels just a little bit "off," there's a good chance the underlying loop is the culprit. Most of us start out using while true do wait() end, but once you want to create something that actually feels professional, you have to move past that and start working with frame-based events.
Why RunService Beats the Standard Loop
Let's be real: the old wait() function is pretty unreliable. It has a minimum delay that's longer than a single frame, and it doesn't really care about the game's frame rate. If the server lags, your wait() lags even more. This is where roblox runservice comes into play. It provides a set of events that fire every single time the game renders a frame or computes physics.
Instead of telling the script to "wait a bit and then do something," you're telling the script to "do this every time the engine breathes." This makes your movements buttery smooth because they're synchronized with the actual refresh rate of the player's monitor. If someone is playing at 144Hz, your code can actually keep up with that, rather than being stuck at the 30-times-a-second limit that older methods often hit.
Breaking Down the Big Three Events
When you dive into roblox runservice, you're mostly going to be dealing with three specific events: RenderStepped, Stepped, and Heartbeat. Choosing the wrong one won't necessarily break your game, but it can cause some weird visual glitches that are a pain to debug later.
RenderStepped
This one is the "VIP" event for local scripts. RenderStepped fires every single frame, right before the frame is actually rendered on the screen. Because of this, it only works in local scripts. If you try to call it from a server script, it'll just throw an error and ruin your day.
You should use RenderStepped for things that are strictly visual. Think of custom camera scripts or updating the position of a crosshair on the screen. Because it runs before the frame renders, any changes you make will be visible instantly in that same frame. However, you have to be careful—if you put a bunch of heavy math or complex logic in here, you'll tank the player's FPS because the game has to finish your script before it can show the next frame.
Heartbeat
Heartbeat is the workhorse of the bunch. It fires every frame after the physics simulation has finished. Unlike RenderStepped, this works on both the client and the server. It's the go-to choice for most general tasks. If you need a part to move, a timer to countdown, or a NPC to check its surroundings, Heartbeat is usually the safest bet. It doesn't block the rendering process, so even if your code takes a millisecond too long, it won't immediately make the screen stutter in the same way.
Stepped
Stepped is a bit more niche but super important for physics-heavy games. It fires before the physics simulation happens. If you're trying to manually adjust the velocity of a part or manipulate how a character interacts with a platform, Stepped is your friend. It ensures your logic is processed right before the engine calculates where everything should land in the next step of the simulation.
The Secret Sauce: DeltaTime
One of the coolest things about roblox runservice is that every one of these events passes a little piece of data called deltaTime. If you aren't using this, you're missing out on the best way to make your game run consistently on different computers.
DeltaTime is essentially the amount of time that has passed since the last frame. Why does this matter? Well, imagine you have a part moving at 5 studs per frame. On a high-end PC running at 120 FPS, that part is going to fly across the map. On a potato phone running at 30 FPS, it's going to move like a snail.
By multiplying your movement values by deltaTime, you make the movement frame-rate independent. It ensures that the part moves at a specific speed per second, regardless of how many frames the user is getting. It's a simple trick, but it's the difference between a game that feels "indie" and one that feels "polished."
Handling Connections Without Leaking Memory
A common trap I see people fall into is connecting to roblox runservice and then just leaving it there. Every time you use :Connect(), you're telling the engine to keep that bit of code running forever. If you have a script that starts a Heartbeat connection every time a player opens a menu, but you never disconnect it, you're creating a memory leak.
Eventually, the game will start to chug because it's trying to run fifty different versions of the same loop in the background. It's always a good habit to store your connection in a variable, like this:
local myConnection = RunService.Heartbeat:Connect(function(dt) -- code here end)
And then, when you're done with it (like when the menu closes or the part is destroyed), call myConnection:Disconnect(). It's a small step that saves you a lot of performance headaches down the road.
Practical Uses in Your Game
So, what can you actually do with all this? A classic example is a custom hovering animation for an item. Instead of using a TweenService that might be overkill, you can use a Heartbeat loop to slightly adjust the Y-axis of a part using a sine wave. It's lightweight, looks smooth, and gives you total control over the movement.
Another great use case is for raycasting. If you're making a projectile system, you don't want to rely on the built-in physics engine to handle high-speed bullets—they'll often phase right through walls. Instead, you can use roblox runservice to cast a small ray every frame from the bullet's current position to its next position. This ensures that even at crazy high speeds, the bullet will always "hit" the wall because you're checking the path every single step of the way.
Finding the Balance
While it's tempting to put everything into a roblox runservice loop, you've got to find a balance. Not everything needs to happen every single frame. If you're updating a leaderboard or checking a player's inventory, a simple event-based system or a slower loop is much better for performance.
The key is to ask yourself: "Does the player need to see this update instantly to feel the immersion?" If the answer is yes—like with movement, cameras, or real-time effects—then RunService is exactly what you need. If the answer is no, keep it simple and save those precious CPU cycles for the stuff that really matters.
In the end, mastering these events is what separates someone who just "makes scripts" from someone who "builds engines." It gives you a level of control over the game's heartbeat that you just can't get anywhere else. Once you get used to the workflow of connecting, disconnecting, and using DeltaTime, you'll probably find it hard to go back to the old ways of scripting.