# Frame Rate & Display Refresh > **Short version:** the `fps` number in the status bar counts the frames your > window actually puts on screen. If it reads lower than your monitor's refresh > rate and the editor still feels responsive, the most likely cause is your > browser — not your graph and not Rhizomium. See > [Known limitation](#known-limitation-multi-monitor-refresh-rates-on-chrome--windows). --- ## What the number means The status bar's `fps` readout counts **presented frames** — frames the browser actually handed to your display. It is the same thing a game's FPS counter reports, and it is the only rate you can actually see. It follows your display. A 60Hz monitor reads ~60, a 120Hz laptop panel reads ~120, a 144Hz one reads ~144. There is no fixed target it is measuring against. The preview panel's overlay shows the same number alongside a second one: ``` 120 fps · 4.2 ms GPU ``` - **`fps`** — frames your window presented. What you see. - **`ms GPU`** — how long the GPU spent on a frame. What your graph costs. Reading them together tells you where a problem is: | Reading | Meaning | | --- | --- | | `120 fps · 4 ms GPU` | Healthy. GPU has headroom. | | `30 fps · 31 ms GPU` | **Your graph is too heavy.** The GPU is the bottleneck — simplify it, or lower the preview resolution. | | `48 fps · 5 ms GPU` | **Not your graph.** The GPU is finishing frames quickly but they are not reaching the screen. Almost always the limitation below. | That third row is the one that confuses people, and it is why the two numbers are shown separately. --- ## Known limitation: multi-monitor refresh rates on Chrome / Windows **If you run more than one display at different refresh rates, Chrome may cap every one of its windows to a single lower rate — including Rhizomium.** This is a browser-level limitation. Native applications give each window the refresh rate of the display it is on. A browser composites all of its windows through one pipeline on one clock, and in mixed-refresh setups it can pick the wrong one. Every tab and every window is affected equally. ### How to tell that this is what you are hitting 1. **Open any other web page** — a blank tab, any website — and run the check below. If that page shows the same low number, the cap is browser-wide and has nothing to do with Rhizomium. 2. **Check a native application** on the same display. If your desktop and other apps are smooth while every browser window is not, that confirms it. 3. **Unplug the second display** and re-check. If the number jumps to your panel's full rate, the cap came from the display combination. ### Measuring it yourself Open the browser console (**F12** → Console) and paste this. It reports the actual spacing between presented frames over about three seconds: ```js (() => { const g = []; let last = performance.now(); const k = (now) => { g.push(now - last); last = now; if (g.length < 200) requestAnimationFrame(k); else { g.shift(); const s = g.slice().sort((a, b) => a - b); console.log('median', s[s.length >> 1].toFixed(1), 'ms →', (1000 / (g.reduce((a, b) => a + b, 0) / g.length)).toFixed(1), 'fps'); } }; requestAnimationFrame(k); })(); ``` | Result | What it means | | --- | --- | | A single tight cluster (e.g. every frame ~20.8 ms) | A hard clock at that rate. Nothing is being dropped — the browser is simply presenting at 48Hz. This is the limitation above. | | A mix of ~16.7 ms and ~33.3 ms | Frames genuinely being dropped on a 60Hz display. That *is* a workload problem — check the `ms GPU` figure. | | Wide scatter | Variable refresh rate (VRR / G-Sync / FreeSync / ProMotion) doing its own pacing. | `chrome://gpu` → search for **"Display refresh rate"** shows what Chrome believes your display is running at. ### What you can do about it None of these are things Rhizomium can do for you — they are display and browser settings: - **Set your displays to the same refresh rate.** Windows: Settings → System → Display → select each display → Advanced display → Choose a refresh rate. Projectors and TVs often negotiate a 24Hz or 48Hz film mode, which is a common source of an oddly specific cap. - **Change which display is primary.** Windows: Settings → System → Display → select the display → "Make this my main display". - **Try a different browser.** Firefox uses a different compositor and may not have the same behaviour on your setup. - **Change the display combination.** If one particular monitor drags the clock down, running without it restores the full rate. ### Why Rhizomium does not "fix" this It cannot. The application cannot make the browser present more frames than the browser's compositor is producing — there is no setting, canvas option, or rendering trick that raises that ceiling from inside a web page. It applies identically to a blank page with no graphics on it at all. What Rhizomium *does* do is report the rate honestly rather than displaying a target and pretending. If the readout says 48, you are seeing 48. --- ## Getting the most out of a high-refresh display If your display runs above 60Hz, check your timing mode: **Preview / Export Settings → Timing → Timing Mode** - **V-Sync (display refresh)** — renders one frame per display refresh. On a 120Hz or 144Hz panel this is what gives you motion at the full rate. - **Fixed step** — renders at the rate set by the Frame Rate slider, regardless of your display. Useful when you need a deterministic rate; on a 120Hz display a fixed 60 caps your motion at 60 even though the display could show twice that. If you are on a high-refresh panel and motion looks smoother in other applications, this setting is worth checking first. --- ## When the frame rate really is your graph If `ms GPU` is high (above ~16 ms), the GPU is the limit and the fixes are in your patch: - Lower the preview resolution — **Preview / Export Settings → Quality** - Reduce compute node resolution and iteration counts - Check the [Performance Profiler](profiler.md) to find which dispatches cost the most - See [Performance Tips](performance.md) for the full list --- ## See also - [Performance Tips](performance.md) - [Performance Profiler](profiler.md) - [Frame Timing Monitoring](frame-timing-monitoring.md) - [Dual Screen Setup](dual-screen.md) - [Troubleshooting](troubleshooting.md)