Check Your Squarespace Site Speed
Run a Lighthouse audit on your Squarespace site and export the full JSON report. Squarespace controls most of the platform code, but these reports show which parts of your design and content choices are hurting your Core Web Vitals.
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Loading...Common performance issues on Squarespace sites
These are the issues most frequently found in Squarespace Lighthouse audits. Your report will tell you exactly which ones apply to your site.
Heavy Squarespace platform JavaScript
Squarespace loads a substantial JavaScript framework on every page. This is platform-level TBT that you cannot fully eliminate, but you can avoid stacking more scripts on top of it.
Large hero background images
Full-screen banner sections are a Squarespace staple but are a major LCP bottleneck if the image is large and uncompressed. Squarespace does not always optimize hero images automatically.
Custom code blocks adding render-blocking scripts
Third-party scripts (booking widgets, chat, marketing pixels) added via Code Injection are loaded synchronously in the <head> and block all rendering.
Fonts from multiple sources
Squarespace sites often load fonts from both Squarespace's CDN and Google Fonts simultaneously, each requiring a separate connection and blocking text rendering.
Pro tip: Squarespace allows custom code injection — add <link rel="preload" as="image"> for your most important above-the-fold image in the <head> injection area to markedly improve LCP with a single line of HTML.
Frequently asked questions
How do I check my Squarespace site speed?
Enter your Squarespace URL at speedexporter.com and run a free Lighthouse audit. Squarespace controls most platform code, so your report helps you understand which issues are platform-level versus content and configuration decisions you can fix yourself.
What causes poor Core Web Vitals on Squarespace?
The main causes are Squarespace's platform JavaScript framework (significant TBT that is largely unavoidable without changing platforms), large hero background images (Squarespace does not always auto-optimize them), and third-party scripts added via Code Injection loading synchronously in the head. Fonts loading from multiple sources (Squarespace CDN + Google Fonts) are also a common FCP issue.
How do I improve Core Web Vitals on Squarespace?
Compress hero images manually before uploading (target under 200KB for desktop hero images). Move Code Injection scripts to the Footer injection area instead of the Header to prevent them blocking render. Remove third-party scripts from Code Injection that you do not actively use. Limit your site to one font family to reduce font loading connections. Export your Lighthouse JSON and paste it into ChatGPT to identify which design choices are causing the most impact.