The technology often used to enhance the performance of user interface interactions is JavaScript, particularly with frameworks like React or Angular. These technologies allow developers to create dynamic and responsive web applications by manipulating the Document Object Model (DOM) in real time. This results in smoother user experiences, as actions like clicks or inputs can trigger immediate visual feedback without the need to refresh entire web pages. Additionally, integrating AJAX allows for asynchronous data loading, enhancing interactivity and performance further.