The Lightning Component framework uses JavaScript on the frontend. Hence, anything that improves JavaScript performance should be considered.

Some of these techniques include the following: 

• Image optimization, by using Lightning:icon and Lightning:buttonIcon.
• Using minified JavaScript bundle if you are using any third-party JavaScript library for production releases. It is recommended not to use any third-party libraries if the framework can do the work for you.
• Using a bundler, such as Webpack Bundler with CSS Purify to minify JavaScript and remove unnecessary selectors.
• Using console.time(), console.timeEnd,  and  performance (https://developer.mozilla.Org/en-US/docs/Web/API/Performance)  APIs to gather metrics to uncover performance issues.