Web fonts significantly impact page load performance. Font loading can delay text rendering and cause layout shifts. Self-host fonts instead of relying on third-party CDNs. WOFF2 format offers best compression for modern browsers. Subset fonts to include only needed characters. font-display: swap renders fallback text immediately. Preload critical fonts with . Inline font declarations in critical CSS. Variable fonts reduce file count with adjustable weight/width. Font loading strategies affect Cumulative Layout Shift metric. Size-adjust property prevents fallback layout shift. subsetting loads only required scripts. Preconnect hints establish early connections to font origins. Font Face Observer enables JavaScript font loading control. Cache fonts aggressively with long max-age headers. FOIT (Flash of Invisible Text) vs FOUT (Flash of Unstyled Text). system-ui stack eliminates font downloads for system fonts. CSS font-display descriptor refines loading behavior. Google Fonts optimization with display=swap parameter. Performance budget includes font file sizes. Fast font loading improves perceived performance and Core Web Vitals.