A search engine system is described herein that provides an alternative data path for collecting results provided by index servers. The alternative data path collects the results in a direct and asynchronous manner; this is in contrast to a synchronous path used to deliver search results to end users via one or more aggregator modules. An analysis system can use the alternative data path to collect a large amount of richly descriptive information regarding the performance of the search engine system, circumventing bottlenecks and other constraints that would otherwise be imposed by the synchronous data path. The analysis system can analyze the information collected from the index servers to improve the performance of the search engine system.