Currently we generate a grouped feed by making a separate Elasticsearch query for each lane in the feed. Elasticsearch has a feature that would let us send all these queries out simultaneously:

https://www.elastic.co/guide/en/elasticsearch/reference/current/search-multi-search.html

This would require some rearchitecture but it would dramatically increase the speed of grouped query generation. In one sense this doesn't really matter, because grouped query generation happens in the background. However this might make it possible to generate grouped feeds in the foreground – opening up the possibility that we could dynamically serve different grouped feeds to different types of patrons.