Website Performance Guide: Hit 90+ PageSpeed Without a Rebuild
Test baseline PageSpeed, set a performance budget, audit third‑party scripts, optimize hero images, reserve space for CLS, reduce CSS weight, defer non‑critical scripts, and create a monthly scorecard.
Test baseline PageSpeed, set a performance budget, audit third‑party scripts, optimize hero images, reserve space for CLS, reduce CSS weight, defer non‑critical scripts, and create a monthly scorecard.
Summary
Enterprise sites often become sluggish due to tag sprawl, heavy media, and poorly optimized third‑party scripts. The guide recommends starting with a baseline PageSpeed Insights score and cross‑checking it against Chrome UX Report data to identify the three core Web Vitals that matter most: LCP, INP, and CLS. It then introduces a performance budget that caps JavaScript to 250‑350 KB, CSS to 50‑80 KB, fonts to two families with three weights, and forces images above the fold to be compressed, correctly sized, and lazy‑loaded below the fold. A key step is auditing and trimming third‑party scripts, loading only those that are essential and deferring non‑critical ones to specific pages. Hero elements should use modern formats like AVIF or WebP, hard‑code dimensions, and be preloaded to improve LCP. CLS is addressed by reserving space for images and avoiding dynamic announcement bars that shift content after load. The guide also advises reducing font weight variety, swapping font‑display to swap, and pruning unused CSS. Finally, it proposes a monthly scorecard that tracks PageSpeed, Core Web Vitals, and the top three heavy scripts, with a release gate that blocks new campaigns that violate the budget.
Key changes
- Baseline PageSpeed Insights and Chrome UX Report to identify LCP, INP, CLS
- Performance budget limits: JS 250‑350 KB, CSS 50‑80 KB, fonts two families, images above fold compressed and sized, below fold lazy‑loaded
- Third‑party script audit: load only essential scripts, defer non‑critical ones per page
- Hero image optimization: use AVIF/WebP, hard‑code dimensions, preload
- CLS mitigation: reserve space for images, avoid dynamic announcement bars
- Reduce font weight variety, use font‑display: swap, prune unused CSS
- Monthly scorecard tracking PageSpeed, Core Web Vitals, top three heavy scripts with release gate