What is Lazy Loading?Lazy loading is a performance optimization technique that defers the loading of non-essential resources (images, videos, iframes, JavaScript) until they are needed, typically when the user scrolls close to the element position on the page. By loading only the resources visible in the initial viewport and deferring everything else, lazy loading
What is Lazy Loading?
Lazy loading is a performance optimization technique that defers the loading of non-essential resources (images, videos, iframes, JavaScript) until they are needed, typically when the user scrolls close to the element position on the page. By loading only the resources visible in the initial viewport and deferring everything else, lazy loading reduces the initial page weight that must be downloaded before the page becomes interactive, significantly improving page load speed metrics including LCP and Time to Interactive.
Lazy Loading for SaaS Marketing Sites
Implementing lazy loading on SaaS websites: (1) HTML native lazy loading: add loading=lazy attribute to all img and iframe tags except those in the above-the-fold viewport (critical: the LCP image should use loading=eager, not lazy; applying lazy loading to your hero image dramatically worsens LCP). (2) JavaScript-based lazy loading: for complex scenarios not handled by the native attribute, libraries like lazysizes.js or Intersection Observer API provide more control. (3) Video and iframe lazy loading: always lazy load below-fold embedded videos, YouTube embeds, and third-party iframes (HubSpot forms, chat widgets) that would otherwise load their entire JavaScript and CSS payloads immediately. (4) Test impact: verify lazy loading improvements in PageSpeed Insights and measure LCP before and after to confirm the optimization is helping rather than hurting performance on critical elements.
Frequently Asked Questions
Which images should NOT be lazy loaded on a SaaS website?
Never apply lazy loading to: (1) Your hero image or any large image in the first viewport (this is your LCP element: lazy loading it means the browser waits for the user to scroll before loading the most important visual element, dramatically increasing LCP), (2) Above-the-fold text elements and CTAs that are part of the primary above-fold design, (3) Brand logo in the header (it is always in view on first load). Apply lazy loading to everything else: product screenshots below the fold, team photos, partner logos in a footer trust strip, embedded videos, case study images, and any other content the user will only see after scrolling. A practical rule: the top 500-800px of your page should load eagerly; everything below should use lazy loading.
Does lazy loading affect SEO?
Lazy loading does not negatively affect SEO when implemented correctly. Google recommends lazy loading for performance improvement. Google does render lazy-loaded images during its second crawl wave (JavaScript rendering), so lazily loaded content is still indexed. However, incorrectly implemented lazy loading that uses non-standard JavaScript without proper Intersection Observer implementation may cause Googlebot to not see the lazy-loaded content until rendering is complete. The safest implementation for SEO is the HTML native loading=lazy attribute, which is fully understood and respected by all modern browsers and Googlebot.