Speedometer 3.0: A shared browser benchmark for web application responsiveness

Cross‑engine collaboration and goals

• Speedometer 3.0 is highlighted as the first major browser benchmark built jointly by all three engine teams (Blink/V8, Gecko/SpiderMonkey, WebKit/JavaScriptCore).
• Many see it as a de‑facto standard for measuring web app responsiveness and expect it to drive real optimizations, as earlier Speedometer versions did.

What the score means

• Higher scores are better; the number is a rescaled inverse of total time for a suite of web‑app interactions.
• Rough intuition: halve the time, double the score; a 5% score increase ≈ 5% faster on the subtests (with some nuance due to geometric mean).
• The dial goes to 140 only as a visual scale with headroom; scores can exceed that, but the gauge saturates.

Observed performance patterns

• Desktop: modern high‑end CPUs and Apple Silicon hit ~25–35; mid‑range laptops and older desktops see ~10–20.
• Mobile: recent iPhones typically outscore flagship Android phones by a large margin; some users note their phones beating older laptops.
• Different browsers on the same machine are often close, though per‑device ordering varies (Safari vs Chrome vs Firefox).

Effects of extensions, privacy, and configs

• Ad blockers, content blockers, and Dark Reader can dramatically lower scores, especially on Safari and Firefox.
• Private/incognito modes or disabling extensions often raise scores significantly.
• Timer‑rounding privacy protections can break the test and yield “Infinity” scores.

Bugs and anomalies

• Some report Safari on iOS crashing or killing the test, especially outside private tabs.
• Others see extreme per‑subtest outliers on Firefox, heavily skewing variance.

Mobile and iOS specifics

• On iOS, all browsers use WebKit, but app‑level differences and added overhead still produce noticeably different scores.

Critiques and skepticism

• Several argue real‑world slowness comes more from bloated, complex sites and DOM limitations than from engines.
• There is concern that benchmarks optimize engines while sites (including those of browser vendors) remain heavy and slow.
• Others counter that Speedometer‑driven engine work has already translated into measurable user‑visible gains.

Latency and user experience

• Some users feel modern systems still have higher input latency than old hardware and crave “tactility.”
• Others report no noticeable click/tap lag and emphasize that bad developer choices, not the web platform itself, often cause delays.