Websitespeed impacts both the usability and searchability of a site. Slow load times harm the user experience while fast performances support SEO through positive signals to search engines like Google. Tools from Google help audit and simulate speed to prioritize optimization.
Google PageSpeed Insights offers gratuitous website auditing, providing speed metrics like the First Contentful Paint (how long until any content is visible), Speed Index (perceptual speed score), Time to Interactive (time until page is highly interactive) and Largest Contentful Paint (primary image or content load time). These speed insights help pinpoint where pages fall short and prioritize improvement areas. Developers use these data to troubleshoot bottlenecks and optimize accordingly.
Google also provides the PageSpeed Simulation which replicates the real user experience on desktop and mobile devices based on connection type (desktop: Fast 3G, mobile: Slow 3G). This allows testing web page performance on the device and network types search engine bots encounter. Areas slowing down the First Contentful Paint, Time to Interactive or the Speed Index should be focused on for optimization.
The Google Real User Monitoring goes further in replicating the real world experience, utilizing modern Chrome browsers to test First Input Delay (time between page first paint and ability to interact), Largest Contentful Paint and Cumulative Layout Shift which measures visual stability. These insights align with Core Web Vitals, Google’s framework for user-centric performance metrics. Pages experiencing high First Input Delay, long Largest Contentful Paint or above-average Cumulative Layout Shift need attention.
Core Web Vitals consist of Largest Contentful Paint, First Input Delay and Cumulative Layout Shift. These metrics directly correlate to user perception of load speed and quality. Google incorporated them into their Page Experience algorithms which factoring website performance into search rankings as part of the recent Core Web Vitals update. Therefore, optimizing the Core Web Vitals is significant for SEO.
First Input Delay measures interactivity, time between first paint and when page is ready to user input. Delays above 300 milliseconds negatively impact Page Experience Score. First Input Delay optimization requires prioritizing above the fold content rendering over below the fold resources Techniques to include critical CSS, lazy loading secondary items, prioritizing control flow over layout and minimizing blocking resources.
Largest Contentful Paint represents how long it takes the primary content to load, such as main article text or hero image. Values over 2.5 seconds harm Page Experience. Tactics like deferring non-critical scripts, optimizing images, inlining critical stylesheets and prioritizing visible content speed up Largest Contentful Paint. CDN, image optimizations and responsive image formats also help.
Cumulative Layout Shift calculates layout stability between page updates due to lazy loading content. Shifts higher than 0.1 negatively impact Page Experience. Developers address this by ensuring above fold content loads at once without reflow through techniques to preload critical resources, prioritize control flow and defer non-critical third party widgets and scripts until after load.
Combining key metrics like above threshold First Input Delay, long Largest Contentful Paint or too-high Cumulative Layout Shift lower the Website Performance Score which Google uses alongside traditional SEO factors to derive rankings. Domains with fast page load times tend to rank higher in natural search results. Therefore, regularly auditing Core Web Vitals and optimizing underperforming pages benefits SEO.
Periodic assessments using Google Lighthouse Chrome extension also provide website performance insights through metrics like First Contentful Paint, Speed Index, interactive, Largest Contentful Paint. Lighthouse uncovers optimization opportunities like eliminating render-blocking resources, minimizing above the fold content size, leveraging browser caching, implementing efficient data transfers and ensuring valid HTML/CSS. Commonly observed alerts include "Eliminate needless requests" or "Defer offscreen CSS to improve First Meaningful Paint".
Measuring Core Web Vitals over time and across pages helps prioritize efforts towards the most impactful optimizations. Google's website speed simulator and Real User Monitoring also offer comparison to data from hundreds of millions of real users on actual devices from around the world. Understanding current performance versus peers drives targeted technical changes with search-based return. Periodic testing ensures unintended regressions do not sneak into the website experience.
In conclusion, speed is the future of search engine optimization as machine learning algorithms increasingly consider user experience factors. Monitoring and optimizing website speed metrics such as Core Web Vitals align site performance with user needs, bolstering SEO by delivering a fast, stable experience Google can recommend with confidence. Ongoing speed inspection and fine-tuning keeps page load times rapid while keeping users and search bots happy.