Slow store losing sales every second.Lighthouse 90+ this session.

A PageSpeed score improvement from 18 to 50+ is achievable in a Full Day session for most Shopify themes. The engineer diagnoses the specific bottlenecks using Lighthouse and WebPageTest a score of 18 almost always indicates multiple compounding issues. Common culprits at that score: unoptimised images (no WebP conversion, no lazy loading, no explicit dimensions causing layout shift), render-blocking JavaScript from third-party apps (live chat widgets, review apps, marketing scripts that load synchronously in the document head), excessive unused CSS and JavaScript from Shopify theme features that are installed but not used, and no lazy loading of below-the-fold sections. The engineer addresses the top 3-4 bottlenecks by impact: image optimisation and lazy loading alone typically move a score from 18 to 40+.

Yes. LCP (Largest Contentful Paint) and INP (Interaction to Next Paint) are the two Core Web Vitals most commonly failing on e-commerce sites, and both can be addressed in a Full Day session. For LCP: the largest contentful element is almost always the hero image preloading it with fetchpriority=high, serving it in WebP at the correct display dimensions, and eliminating any render-blocking resources before it loads typically cuts LCP from 4-6 seconds to under 2.5 seconds. For INP: the most common cause is heavy JavaScript event handlers on interactive elements (add-to-cart, variant selector, quantity picker) that block the main thread for 300-500ms the fix is moving computation off the main thread using requestIdleCallback or a web worker, and debouncing input handlers.

Unoptimised product images are almost always a major contributor to slow load times 400 images with no WebP conversion, no lazy loading, and no size constraints can add 2-4 seconds to category and product pages. The engineer implements: automated WebP conversion using Shopify's native image transformation URLs (just appending .webp to any Shopify CDN URL) so you do not need to re-upload all 400 images, lazy loading for all below-the-fold product images using the native loading=lazy attribute, srcset configurations so mobile devices download appropriately sized images rather than full desktop resolution, and explicit width and height attributes on all images to prevent layout shift during load. These changes apply to all current and future product images you do not need to touch each image individually.

Performance improvements are directly correlated with SEO ranking improvements Google has used Core Web Vitals as a ranking signal since 2021. Fixing your PageSpeed score from 18 to 55+ typically leads to measurable organic ranking improvements within 4-12 weeks as Googlebot re-crawls and re-evaluates your pages. The specific signals that affect ranking: LCP (Largest Contentful Paint) pages loading under 2.5 seconds are rated Good, over 4 seconds are rated Poor, with Good pages receiving a ranking boost; INP (Interaction to Next Paint) pages with responsive interactions receive a ranking signal vs. pages with 500ms+ interaction delays; CLS (Cumulative Layout Shift) pages with minimal layout shift are rewarded. PM documents your Core Web Vitals scores before and after the engagement so you have a baseline to track ranking impact.

The five optimisations that deliver the largest performance improvements for e-commerce stores, ranked by typical impact: first, above-the-fold image optimisation hero image WebP conversion, preloading with fetchpriority=high, and correct sizing typically improves LCP by 1.5-2 seconds on its own; second, JavaScript deferral moving third-party scripts (chat widgets, analytics, marketing pixels) to load after the page is interactive reduces Total Blocking Time by 400-800ms; third, lazy loading below-the-fold images product images that are not visible without scrolling should not load until the user scrolls near them, reducing initial page weight by 60-80% for category pages; fourth, unused CSS removal Shopify themes often ship with CSS for features you do not use, removing unused rules reduces stylesheet parse time; fifth, server-side caching of product data caching Shopify Storefront API responses for non-personalised pages (category pages, product pages) eliminates redundant API calls on every page load.