Google's web rendering service queues URLs for a second-pass render after the initial HTML fetch. Rendering can be delayed by hours or days for large sites, and heavy pages that exceed the render budget may be indexed with incomplete content.
What burns budget
- Blocking third-party scripts that stall hydration.
- Very large JavaScript bundles.
- Long client-side data fetches before the first meaningful paint.
- Slow origin server responses.
Example
A marketplace with 500,000 SPA URLs discovers only 30% appear in the index. Migrating to hybrid SSR restores near-complete coverage within a month.
How SEM Optimiser reports it
The audit warns when critical content is only present in the rendered DOM and estimates the render cost per page based on script weight and blocking behaviour.
Related terms
- JavaScript SEO
JavaScript SEO is the practice of ensuring content generated or modified by client-side JavaScript is discoverable, crawlable, and indexable by search engines.
- Crawl Budget
Crawl budget is the number of URLs Googlebot can and will crawl on a website within a given time frame, determined by crawl capacity and crawl demand.
- Core Web Vitals
Core Web Vitals is a set of three page-experience metrics Google uses to measure loading performance, interactivity, and visual stability: LCP, INP, and CLS.