Any view in this system can use SOLR as an alternative back end to MySQL. SOLR is a nosql type database and runs lightning fast compared to conventional databases. Google runs on similar technology.
This system provides normalized API endpoints in both JSON and RSS format. Data is aggregated from all feeds and from content originating from this system.
Feeds are Drupal entities that are run either manually or on regular cron jobs. They read data in remote feeds or APIs on the internet and build things in Drupal based on the logic of the feed. This article explains the low level implementation of feeds ingestion.