Rio on Speedometer 3.1: ahead of Arc, Dia and Zen
On Speedometer 3.1, Rio scored 97.8 with Chrome at 100, in 3 runs each on the same Mac. That is above the published scores for Arc, Dia and Zen: BrowseRating's results put Arc at 91.0% of its Chrome score, Dia at 89.3% and Zen at 76.8%, measured on a different Mac.
The run
Speedometer 3.1 measures how quickly a browser responds when you click and type in web apps. It runs real web app code, from to-do lists to editors and charts, and turns the time into a score where higher is faster.
On November 9, 2026 I ran it on an Apple M4 Max with 36 GB on macOS 26.6.2: Rio 158.0.8127.18 and Chrome 156.0.8078.81, 3 runs each, on the same Mac.
| Browser | Run 1 | Run 2 | Run 3 | Mean |
|---|---|---|---|---|
| Rio | 55.5 | 55.6 | 56.2 | 55.77 |
| Chrome | 56.8 | 56.9 | 57.4 | 57.03 |
Rio's mean over Chrome's mean is 55.77 / 57.03 = 0.978, so Rio's index is 97.8 with Chrome at 100.
Why an index
A Speedometer score depends on the Mac it runs on. An M5 Max scores higher than an M4 Pro with the same browser, so raw scores from different machines can't be compared. Dividing each browser's score by Chrome's score on the same machine removes most of that. What is left says how close a browser gets to Chrome on its own hardware.
That is why every number below is an index against Chrome, and each one names the Mac and the source it came from.
The other sidebar browsers
I have not run Arc, Dia or Zen myself. These are their published results, each divided by the Chrome score from the same source and the same Mac.
| Browser | Score | Chrome on that Mac | Index | Source |
|---|---|---|---|---|
| Rio 158 | 55.77 | 57.03 | 97.8 | Our run, M4 Max, 36 GB |
| Arc 1.167.1 | 47.5 | 52.2 | 91.0 | BrowseRating |
| Dia | 38.70 | 41.40 | 93.5 | Aside's post, M4 Pro, 48 GB |
| Dia | 60.25 | 65.73 | 91.7 | Aside's post, quoting a run on an M5 Max, 36 GB |
| Dia 1.48.0 | 46.6 | 52.2 | 89.3 | BrowseRating |
| Zen | 54.70 | 65.73 | 83.2 | Aside's post, quoting a run on an M5 Max, 36 GB |
| Zen 1.23b | 40.1 | 52.2 | 76.8 | BrowseRating |
Against the highest published number for each:
- Arc: 97.8 against 91.0, 6.8 points.
- Dia: 97.8 against 93.5, 4.3 points.
- Zen: 97.8 against 83.2, 14.6 points.
How careful to be with these numbers
BrowseRating is one independent developer's site that lists Speedometer 3.1 for 38 Mac browsers under one method: 5 runs, drop the best and the worst, average the middle 3. It doesn't publish its hardware beyond macOS on Apple silicon, and its Chrome is version 154. Aside's post comes from a browser maker and quotes clean-profile runs, including the two Macs in the table.
So the comparison is index to index, each against Chrome on its own Mac, and Rio's index is above every published one for Arc, Dia and Zen.
Run it yourself
- Quit other apps and plug in your Mac.
- Open browserbench.org/Speedometer3.1 in Rio and click Start Test. Run it 3 times.
- Do the same in Chrome on the same Mac.
- Divide Rio's mean by Chrome's mean and multiply by 100.
If you post your result, include your Mac's chip, memory and macOS version, so others can compare like with like.
Memory too
Speed is one half. With the same 10 sites open on one MacBook Pro, Rio added 3,573 MB of memory and Arc added 5,385 MB. The method and every run are in Rio uses less memory than Arc on the same 10 sites.
Questions
Is Rio faster than Arc on Speedometer 3.1?
Rio's index is 97.8 against Chrome on our Mac. BrowseRating's published scores put Arc 1.167.1 at 91.0% of its Chrome score, on a different Mac. Rio's index is 6.8 points higher.
What is Speedometer 3.1?
A browser benchmark that measures how quickly web apps respond to clicks and typing, by running real web app code. It is published at browserbench.org.
Which Mac did Rio's run use?
An Apple M4 Max with 36 GB on macOS 26.6.2, on November 9, 2026. Rio 158.0.8127.18 ran against Chrome 156.0.8078.81, 3 runs each.
Where do the Arc, Dia and Zen numbers come from?
From their published results: BrowseRating's macOS ARM rankings, and the runs quoted in a post by the Aside browser's developers. Each is an index against Chrome on that source's own Mac.
