I audit every new client's site with Lighthouse before any work. These causes repeat in 90% of cases:
1. Unoptimized images
Always the number one cause. A 4MB image on a homepage means 10 seconds of loading on an average mobile network. The fix: WebP/AVIF with multiple sizes.
2. Excess third-party scripts
Every tracking tool and chat widget adds hundreds of milliseconds. Keep only what you actually use.
3. No caching
Especially on WordPress — a good caching plugin alone can triple your speed.
