Client-side header bidding vs Google Open Bidding: the latency tax

Client-side header bidding vs Google Open Bidding: the latency tax

Benchmark drop. Auction latency added per method (n=90 sites, 28d):

— Client-side Prebid $▮▮▮▮▮▮▮ 380ms
— Open Bidding (server) $▮▮ 110ms
— Hybrid (4 SSPs client + rest server) $▮▮▮ 160ms

EPMV (earnings per thousand visitors, ad revenue ÷ visitors × 1000) tells the other half. Client-side wins the auction (+8-14% bid density) but loses 3-6% of impressions to timeouts and viewability decay on slow mobile. Open Bidding is leaner but Google takes a revenue-share cut and you lose bid transparency.

Rule: under 2.5s LCP target with 6+ demand partners, go hybrid. Pure client-side only survives on desktop-heavy traffic (>55%).

So what: Hybrid setups beat pure client-side on mobile EPMV ▲ 4.2%.