Raising a header-bidding timeout from 1000ms to 1500ms added 12% revenue

Raising a header-bidding timeout from 1000ms to 1500ms added 12% revenue

Header bidding (publisher-side code that auctions an impression among multiple demand partners in the browser before calling the ad server). A publisher was leaving money on the table through an aggressive timeout.

1. They logged, per auction, which bidders responded inside the 1000ms window versus arrived late and were discarded.
— 23% of bids from two high-value demand partners landed between 1000ms and 1400ms and were thrown out.
2. They split traffic: half kept the 1000ms timeout, half moved to 1500ms.
3. They measured ad revenue and page-load impact on each arm.

Evidence: the 1500ms arm captured those late bids, lifting auction revenue 12%. Largest-Contentful-Paint worsened by only 90ms because ad slots loaded asynchronously below the fold. The discarded bidders had been the ones most often setting the clearing price, so dropping them deflated the whole auction, not just their own slots.

Why it matters: a timeout is a revenue lever, not just a performance setting. The bidders who respond slowest are often the most competitive, and excluding them lowers what every other bidder has to beat.