Measure real users, not lab tests
Lab tools are useful for debugging, but Google ranks on field data from real visitors. Start with your Search Console report and real-user monitoring so you fix what people actually experience.
Interaction to Next Paint is the new battleground
Most sites now pass on loading speed but struggle with responsiveness. Heavy third-party scripts, oversized JavaScript bundles and long tasks on the main thread are the usual culprits.
The quick wins
Serve modern image formats at the right size, preload your main font, defer anything not needed for first paint, and audit every tag manager script. These alone often move a site from amber to green.