What this FAQ covers
This page answers recurring questions about website performance for website owners, agencies, and technical teams. The answers define practical boundaries, identify the evidence that matters, and explain when a question requires account-specific, technical, contractual, or legal review.
- What is the difference between lab and field data?
- What are Core Web Vitals?
- Does a 100 performance score mean the page is fast for everyone?
- What usually makes pages slow?
Use the answers responsibly
Apply each answer to the actual website, scope, agreement, and evidence. Avoid optimizing a synthetic score while making the real user journey worse. When the decision could affect production availability, security, accessibility, billing, privacy, or contractual commitments, document the responsible reviewer and verification plan.
Questions and answers
01What is the difference between lab and field data?
Lab data is collected under controlled conditions for diagnosis. Field data reflects real users, devices, networks, and sessions.
02What are Core Web Vitals?
They are experience-oriented metrics focused on loading, interaction responsiveness, and visual stability.
03Does a 100 performance score mean the page is fast for everyone?
No. A lab score represents one tool, configuration, run, and condition. Real experience varies.
04What usually makes pages slow?
Server response, render-blocking resources, large images, fonts, JavaScript, third parties, inefficient templates, and poor caching are common contributors.
05Should every image be lazy-loaded?
No. Important above-the-fold images may need prioritized loading. Lower-priority images can often be deferred.
06Can caching break a website?
Yes. Misconfigured caching can serve stale, private, or incompatible content. Test authentication, forms, personalization, and invalidation.
07How should performance fixes be verified?
Compare representative lab tests, field data when available, user tasks, errors, and business outcomes after the change.
Turn website performance into an accountable record.
A clear, supportable answer set for website performance linked to the relevant workflow or policy.