To enhance personalization, Mozilla will focus on simplifying extension builds, discovery and usage, and provide more APIs. On the mobile side, Firefox Klar will optimize performance and rewrite.
To counter the risks of tracking, intrusive advertising, and other users, Firefox will by default filter certain types of ads, block cross-domain tracking, enhance tracking protection, provide global entitlement management, block auto-play videos, introduce Breach Alerts, warn users of their The website being browsed has been compromised.
Source: Mozilla