Browser plugins, especially Flash, have enabled some of our favorite experiences on the Web, including videos and interactive content. But plugins often introduce stability, performance, and security issues for browsers. This is not a trade-off users should have to accept.
Mozilla and the Web as a whole have been taking steps to reduce the need for Flash content in everyday browsing. Starting in August, Firefox will block certain Flash content that is not essential to the user experience, while continuing to support legacy Flash content. These and future changes will bring Firefox users enhanced security, improved battery life, faster page load, and better browser responsiveness.
Over the past few years, Firefox has implemented Web APIs to replace functionality that was formerly provided only by plugins. This includes audio/video playback and streaming capabilities, clipboard integration, fast 2D and 3D graphics, WebSocket networking, and microphone/camera access. As websites have switched from Flash to other web technologies, the plugin crash rate in Firefox has dropped significantly:
Full Article: https://blog.mozilla.org/futurereleases/2016/07/20/reducing-adobe-flash-usage-in-firefox/
