Transaction speed in a Decentralized Exchange (DEX) refers to the rapid processing of trades and transfers without the need for intermediaries. This feature is crucial as it allows users to execute trades almost instantaneously, enhancing the overall trading experience. By leveraging blockchain technology, DEXs can facilitate peer-to-peer transactions directly between users, significantly reducing latency and increasing the efficiency of the trading process. This is particularly important in volatile markets where timing can be critical to capitalizing on price movements.