Staff Firefox Performance Engineer

Why Mozilla? Mozilla Corporation is the non-profit-backed technology company that has shaped the internet for the better over the last 25 years. We make pioneering brands like Firefox, the privacy-minded web browser. Now, with more than 225 million people around the world using our products each month, we’re shaping the next 25 years of technology and helping to reclaim an internet built for people, not companies. Our work focuses on diverse areas including AI, social media, security and more. And we’re doing this while never losing our focus on our core mission – to make the internet better for people. The Mozilla Corporation is wholly owned by the non-profit 501(c) Mozilla Foundation. This means we aren’t beholden to any shareholders — only to our mission. Along with thousands of volunteer contributors and collaborators all over the world, Mozillians design, build and distribute open-source software that enables people to enjoy the internet on their terms. About this team and role: The Mozilla Firefox Performance team is a community of engineers who care deeply about delivering the fastest browser possible. We are the team responsible for making all parts of the browser go fast. Our team is geographically-distributed, and working in the open is the norm. We contribute to the code driving the Firefox browser on a number of platforms - Windows, Android, Linux, and macOS. Our focus is on finding and fixing things that slow down the browser as well as helping other teams write fast and reliable code to make Firefox excellent for users. Do you value curiosity and enjoy finding a needle in a haystack? Do you approach problems by looking at the system as a whole? Do you want to help lead and shape the future of the Internet? Do you like making things blazingly fast? If so, we’d love to hear from you. What you'll do: • Write code and tests, build prototypes, tackle problems, profile and analyze performance bottlenecks • Learn about a wide variety of problems and solutions across a large, complex, and evolving codebase • Use several programming languages (e.g., C++, JavaScript, Kotlin, Rust, Python) and techniques to fix performance issues, with an emphasis on C++ and JavaScript • Help to educate engineers on other teams about writing more performant code through code reviews, giving talks, implementing tooling, and/or writing documentation • Break down complex performance problems into actionable next steps and drive them to completion • Partner with engineering teams across the organization to support performance efforts, and lead them within your area • Contribute to the direction of performance benchmarks and help prioritize the improvements that matter most • Own the performance of a significant area of the browser end to end, and contribute to the Performance team's technical roadmap • Work with driven, committed team members to help bring the Open Web to millions of people What you'll bring: • BS/MS in CS or CE, and 5+ years of relevant experience • Deep proficiency in C++ • Working proficiency in JavaScript • You have proven experience developing performance-critical software • You take an experimental and measured approach to solving problems (measurement, and using experiments to diagnose an issue or prove out a solution) • Proven skill in debugging and analyzing performance bottlenecks, and using profiling tools to diagnose and fix issues (VTune, Xperf, other sampling based profilers) • Experience with at least one of: multithreading and concurrency, disk I/O, or GPU work • Track record of driving projects to completion, including work spanning more than one engineer. • Experience collaborating with engineers on other teams to deliver shared goals. • An interest and ability to work in a distributed t