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Experiment · exp-002 · Feature flag · server-side · flag: vip-lazy-load-v1 · VIP
VIP gallery lazy loading
~Inconclusive
Listings · QCT · 2025-10-01 – 2025-10-22 · 21 days · max.mueller@mobile.de
Created in Kameleoon on 2025-09-20 - 11 days before the experiment launched.
What it was
VIP pages load all listing images eagerly, including those below the fold. On mobile connections this caused LCP scores above 4s for listings with 12+ photos. The hypothesis was that lazy-loading images below the first two would reduce LCP and increase scroll depth, with no penalty to contact rate — buyers who scroll further into a gallery have demonstrated higher intent. Tested via a server-side feature flag on 50% of mobile VIP traffic.
What we learned
Learning
Lazy loading reduced mobile LCP p75 from 4.1s to 2.6s — a meaningful Core Web Vitals improvement. Gallery scroll depth increased by 11%. However, dealer contact rate showed no improvement (+0.3%, CI: -1.4% to +2.0%, reliability 0.31). Inconclusive on the primary business metric. Performance win is real but insufficient alone to justify the product change. Scheduled follow-up: test whether a "View all photos" CTA above the fold drives the contact lift we expected from scroll depth.
max.mueller@mobile.de · 2025-10-28 · current
TouchpointVIP