If you’ve ever noticed your frame rate drop when dragging your editing window from your laptop screen to an external monitor, you’re not alone. It’s one of those moments that can make you pause—especially if you’re working with real-time previews, overlays, or GPU effects. But before you assume something’s wrong with your computer or editing app, here’s the good news: it’s completely normal.

Let’s break down what’s actually happening—and why it’s not a problem at all.

Frame Rate Follows the Display

Creative applications often rely on something called requestAnimationFrame (or rAF for short). This feature tells the app when to redraw the screen, and it’s usually synced to the refresh rate of your display. So, if your screen updates 60 times per second (60 Hz), your app will try to match that with 60 frames per second (fps). It’s a smooth, efficient way to keep visuals in sync with your hardware.

Now here’s where things get interesting: not all screens refresh at the same rate. Your laptop’s built-in display might run at 60 Hz, but your external monitor could be running at 30 Hz, 75 Hz, 120 Hz, or something else entirely. And when you move your window from one screen to another, the browser or system automatically adjusts to match the new screen’s refresh rate.

For example, if you’re working on a MacBook Air, the built-in Retina display typically runs at 60 Hz. Your app or overlay would render at 60 fps there. But if you drag the window onto a 27-inch external monitor that runs at 30 Hz, the browser will drop the frame rate to 30 fps to stay in sync with that monitor. That change happens automatically—and it’s intentional.

Power Saving and System Behavior

On top of matching display refresh rates, other system factors can influence the frame rate as well. On macOS, for instance, if you connect a 4K external monitor, your computer might switch to a low-power GPU mode to conserve energy. In some cases, this limits the frame rate to 30 fps even if your screen technically supports more. It’s a built-in feature to keep things efficient when you’re on battery or using energy-saving hardware.

There’s also something called system compositor overhead, especially on macOS, where the operating system works hard to coordinate visuals across multiple screens with different pixel densities. If your external display is running a non-Retina mode while your laptop screen uses Retina, macOS might limit the frame rate to keep both displays in harmony. Again, this isn’t a bug—it’s the system doing its job.

Does It Affect Your Editing or Overlay?

Not at all. As a photographer or creative professional, your main concern is whether your app is keeping up with the screen’s natural refresh rate. If you see 60 fps on one screen and 30 fps on another, that just means your app is drawing exactly once per refresh, as it should. It doesn’t mean your system is struggling or your editing tools are underperforming.

In fact, this syncing behavior is helpful. It ensures that heavy code changes or visual effects aren’t accidentally slowing things down beneath what the screen can handle. As long as the app stays in sync with the display’s refresh rate—whatever that rate happens to be—you’re getting optimal performance.

Want to Go Deeper?

If you’re curious about analyzing performance more precisely, consider tracking render time per frame instead of relying solely on frames per second. For example, if each frame of your app takes 16 milliseconds or less to render, it will easily support 60 fps on a 60 Hz display—and run even more smoothly on slower screens. It’s a more reliable way to measure how efficiently your app is working, especially across different displays.

For diagnostics, developers sometimes use timers that aren’t tied to the display refresh rate at all. A tool like setInterval can give you an independent view of CPU or GPU usage without being affected by the current screen’s sync rate.

Final Thoughts

So if you’re previewing an image, applying a LUT, or working with real-time sliders and see your frame rate dip when switching screens, don’t stress. That drop from 60 to 30 fps (or any other rate) is your system adapting to the hardware it’s connected to. It’s a sign that everything is syncing correctly—not that something is wrong.

In short: the app follows the screen. And that’s exactly what it’s supposed to do.