The search engine plays an essential role in e-Commerce: it connects the user's need with a set of relevant items based on a query. This is not a simple task; millions of queries per second need to be processed over possibly billions of items, and it is expected that every query will be executed in just a few hundred milliseconds using limited resources. In this article, we show how we improved eBay's search engine efficiency by over 25%, inspired by a technique coming from web search.