Check Your Gatsby Site Speed
Run a Lighthouse audit on your Gatsby site and export the full JSON report. Despite Gatsby's performance reputation, modern audits reveal real gaps to address — export the JSON and get AI-powered fixes.
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Loading...Common performance issues on Gatsby sites
These are the issues most frequently found in Gatsby Lighthouse audits. Your report will tell you exactly which ones apply to your site.
JavaScript hydration overhead
Gatsby ships full React JavaScript to the client even for static pages, causing TBT to spike during hydration. Pages with complex component trees can have TBT over 500ms.
Gatsby Link prefetching causing blocking
Gatsby's aggressive link prefetching can consume bandwidth and main thread time on pages with many internal links, increasing TBT for users on slower connections.
Third-party plugins adding JavaScript
Popular Gatsby plugins (Google Analytics, Drift, Intercom) inject scripts that run on every page and frequently become the primary TBT contributor.
GraphQL data fetching increasing build complexity
Complex GraphQL queries in page components can cause unnecessary data to be embedded in page bundles, increasing JavaScript payload size.
Pro tip: Gatsby's gatsby-plugin-image automatically handles WebP conversion, responsive images, blur-up loading, and HTML width/height attributes. If you're still using the deprecated gatsby-image, migrate immediately — it removes a significant LCP and CLS issue in one step.
Want a detailed tutorial? Read our step-by-step performance fix guide →
Frequently asked questions
How do I check my Gatsby site speed?
Enter your Gatsby site URL at speedexporter.com and run a Lighthouse audit. Despite Gatsby's performance reputation, React hydration, third-party plugins, and aggressive prefetching create real issues — the full JSON report identifies exactly which audits you are failing and the estimated savings for each fix.
What causes slow performance on Gatsby sites?
The main causes are JavaScript hydration overhead (Gatsby ships full React to the client for every page, causing TBT spikes during hydration), third-party Gatsby plugins that inject analytics and chat scripts on every page, and aggressive link prefetching consuming bandwidth on pages with many internal links. Staying on deprecated gatsby-image instead of gatsby-plugin-image is a major LCP and CLS issue.
How do I pass Core Web Vitals on a Gatsby site?
Migrate from gatsby-image to gatsby-plugin-image if you have not already — it handles WebP, explicit dimensions, and LCP priority automatically. Audit your installed Gatsby plugins and remove any that add scripts you do not actively use. Export your full Lighthouse JSON from PageSpeed Exporter and ask Claude for plugin-specific config changes based on your actual failing audits.