An SSD (Solid State Drive) plays a crucial role in improving computer performance by providing faster data access speeds compared to traditional hard drives. SSDs use flash memory to store data, allowing for quicker boot times, faster application loads, and overall enhanced system responsiveness. Their lack of moving parts also means they are more durable and consume less power, making them suitable for mobile devices. Upgrading to an SSD can significantly enhance user experience, especially in tasks requiring heavy data processing and multitasking.