Product images killing my mobile speed — 4.8s LCP
PageSpeed gives me 34 on mobile, 89 on desktop. The killer is LCP at 4.8s on product pages.
My photos are 3000px wide JPEGs straight out of Lightroom, roughly 1.2MB each, and there are six per product. Do I resize before upload or is there a proper way to handle this on Shopify?
4 replies
Adding to that: check your theme is not requesting the master file in the gallery. Some themes use img_url with no size parameter and quietly serve the 3000px original.
Never upload straight from Lightroom. Export at 2048px on the long edge, quality 70, and let Shopify serve WebP from there. You will drop from 1.2MB to about 180KB with no visible difference on a phone.
Then only the first image should be eager loaded — the other five want loading="lazy". That alone usually takes a second off LCP.
Worth measuring conversion in a fortnight too — we saw about 8% more mobile checkouts after a similar fix.
Re-exported 40 products last night at 2048/70 and mobile went from 34 to 71. LCP now 2.1s. Genuinely did not expect that much.
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