If you’re finding that a website containing a lot of JavaScript is performing badly on a particular browser/device you can run the Browserbench.org Speedometer (link goes to v2.0, but newer versions are now available). That will check the performance of that device and you can then compare it against some known results.
Here are a few Browserbench.org Speedometer 2.0 results from devices I had access to from September 2019 to April 2025.
| Device | Processor | OS | Browser | Result |
|---|---|---|---|---|
| iPhone 15 Pro Max | A17 Pro | iOS 18.4.1 | Safari 18.4 | 515 |
| iPhone SE (2020) | A13 Bionic | iOS 15.4.1 | Safari 15.4 | 190 |
| iPhone SE (2020) | A13 Bionic | iOS 13.4.1 | Safari 13 | 152 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Ventura 13.7.5 | Edge 135.0.3179.98 | 151 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Ventura 13.7.5 | Safari 18.4 | 108 |
| Lenovo P320 | Xeon E3-1245 v6 @3.7 GHz | Windows 10 Pro 21H2 | Edge 106.0.1370.47 | 103 |
| Lenovo P320 | Xeon E3-1245 v6 @3.7 GHz | Windows 10 Pro 1809 | Chrome 77.0.3865.90 | 98.2 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Ventura 13.1 | Edge 109.0.1518.70 | 90.8 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Ventura 13.1 | Safari 16.2 | 86.9 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Ventura 13.1 | Firefox 109.0 | 80.0 |
| Lenovo P320 | Xeon E3-1245 v6 @3.7 GHz | Windows 10 Pro 1809 | Firefox 68.02 | 80.6 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Catalina 10.15.7 | Safari 15.4 | 78.3 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Catalina 10.15.7 | Firefox 99.0.1 | 77.37 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | Mac OS X Mojave 10.14.6 | Safari 13.1 | 70.7 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | macOS Catalina 10.15.7 | Edge 101.0.1210.32 | 62.6 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | Mac OS X High Sierra 10.13.6 | Safari 13 | 60.9 |
| Lenovo P320 | Xeon E3-1245 v6 @3.7 GHz | Windows 10 Pro 1809 | Edge 44.17763.1.0 | 58.9 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | Mac OS X Mojave 10.14.6 | Firefox 75 | 57.1 |
| iPhone SE | A9 APL1022 | iOS 13.1.2 | Safari | 50.2 |
| MacBook Pro Mid 2012 | Core i7 2.3 GHz | Mac OS X High Sierra 10.13.6 | Firefox 69.01 | 47.41 |
| iPhone SE | A9 APL1022 | iOS 12.4 | Safari | 42.7 |
| iPhone 6 | A8 APL1011 | iOS 12.4.1 | Safari | 24.7 |
| iPhone 6 | A8 APL1011 | iOS 12.4.1 | Firefox Focus | 25.5 |
| iPhone 6 | A8 APL1011 | iOS 12.4.1 | Opera | 16.58 |
| ASUS Nexus 7 tablet K008 | Qualcomm Snapdragon S4 Pro | Android 6.0.1 | Chrome 75.0.3770.101 | 7.93 |
As you can see on the same hardware, the choice of browser and OS version can make a big difference.
