Building a high-performance crypto news aggregation system using Dragonfly's JSON and SEARCH APIs can be achieved by first preparing and storing the data in Dragonfly, creating a basic search index, identifying the most mentioned cryptocurrencies over a period, tracking recent mentions of a specific cryptocurrency, and evaluating sentiment for a particular cryptocurrency. The solution utilizes Dragonfly's FT.AGGREGATE and FT.SEARCH queries to efficiently process and analyze crypto news for better decision-making.