Staff Firefox Performance Engineer

Role overview Help shape the future of a major open-source web browser on Windows, Android, Linux, and macOS. The Performance team is a distributed group of engineers dedicated to making every part of the browser fast, identifying bottlenecks, and partnering with other teams to ship performant code. This is a hands-on staff-level role owning the performance of a significant area of the codebase end to end.

Responsibilities - Write code and tests, build prototypes, and profile and analyze performance bottlenecks across a large, evolving C++ and JavaScript codebase. - Use multiple languages including C++, JavaScript, Kotlin, Rust, and Python, with primary emphasis on C++ and JavaScript. - Break down complex performance problems into actionable steps and drive them to completion across more than one engineer. - Educate other engineers through code reviews, talks, internal tooling, and documentation that promote performant coding practices. - Contribute to benchmark direction and help prioritize the improvements that matter most to users. - Own performance for a significant browser area end to end and help shape the team's technical roadmap.

Requirements - BS or MS in computer science or computer engineering, plus five or more years of relevant industry experience. - Deep proficiency in C++ and working proficiency in JavaScript. - Proven track record developing performance-critical software and an experimental, measurement-driven approach to problem solving. - Skill in debugging and analyzing bottlenecks using sampling-based profilers such as VTune or Xperf. - Experience with at least one of: multithreading and concurrency, disk I/O, or GPU work. - Demonstrated ability to drive projects to completion and collaborate across teams in a distributed environment, with strong asynchronous written communication.

Nice to have - Familiarity with web standards or common web patterns. - Familiarity with Android or Windows application programming. - Solid understanding of statistics. - Prior experience working on a modern web browser.

Benefits and work setup - Fully remote within eligible US locations; the listed US hiring range spans approximately $139,000 to $218,000 depending on tier, with the posted range shown on the requisition as the authoritative figure. - Benefits include comprehensive medical, dental, and vision coverage; generous retirement contributions with immediate vesting; quarterly company-wide wellness days; country-specific holidays plus a birthday day off; a one-time home office stipend; an annual professional development budget; a quarterly well-being stipend; and considerable paid parental leave.