Bootstrap Passes Core Web Vitals on 45.7% of Mobile Sites. Tailwind Manages 36.8%

    We matched Chrome field data to the CSS framework on 3 million sites. Bootstrap sites pass Core Web Vitals more often than Tailwind sites on mobile (45.7% vs 36.8%), but the difference is not the CSS. It is the JavaScript stack each framework travels with.

    Core Web Vitals pass rate, Bootstrap vs Tailwind (mobile)
    Bootstrap
    45.7%
    Tailwind CSS
    36.8%

    Source: PageSpeed Matters analysis of 3 million origins with CrUX field data, May 2026.

    The framework everyone calls heavier passes 8.9 points more often on phones.

    Good responsiveness (INP), Bootstrap vs Tailwind (mobile)
    Bootstrap
    89.2%
    Tailwind CSS
    73.7%

    Source: PageSpeed Matters analysis, mobile 75th-percentile field data, May 2026.

    Tailwind is the styling default of the modern JavaScript ecosystem, and it carries that stack's main-thread cost.

    Source: Bootstrap Passes Core Web Vitals on 45.7% of Mobile Sites. Tailwind Manages 36.8% - PageSpeed Matters