Today, web browsers are just as complex as operating systems. However, I believe there is a need to rethink our approach on how to architect such software system. In this talk, I will talk you on a tour of new ideas and challenges that pertain to browser security, privacy, and performance. I will talk about issues surrounding a new wave of browser performance wars. I will touch upon a range of issues related to user tracking, ad blocking, anti-ad blocking, coin mining. I will discuss our efforts to push the performance envelope further, while lowering the power consumption. Finally, I will talk about the challenges of building privacy-preserving delivery mechanisms in the browser. My focus is what is already part of Brave, and what we still consider needs to be added.