What Lighthouse lift can I realistically expect?

Measured across the 23 Hyvä migrations I’ve shipped (2023-2026), mobile Lighthouse performance score:

• Before (Luma, default config): median 28, range 12-52.
• Before (Luma, perf-tuned): median 41, range 28-68.
• After (stock Hyvä): median 92, range 84-98.
• After (Hyvä + perf-tuned): median 97, range 94-99.

The non-obvious wins beyond the score number:

• LCP: typically drops from 3.5-6s on Luma to 1.0-1.6s on Hyvä. Biggest single conversion-lift driver.
• INP: typically drops from 350-800ms (Luma + jQuery + Knockout) to 60-180ms (Hyvä + Alpine). Big on mobile checkout INP, passing the 200ms Core Web Vital threshold matters for both rankings and conversion.
• JS bundle size: Luma ships ~800KB, 1.5MB of JS on first render. Hyvä ships 30-80KB (Alpine + your sprinkles). 10-30x reduction.

The 95+ floor is robust as long as your backend is healthy (server response time <500ms TTFB). If your hosting is undersized, Hyvä still helps but won’t alone get you to 95+.