Staff Firefox Performance Engineer

liv; United States; Remote; USD 140,000 - 210,000; Full time

Benefits offered by this job

Competitive compensation

Excellent medical/dental/vision

Retirement contributions

Home office stipend

Job summary

Mozilla Corporation is seeking a performance-focused software engineer with deep C++ expertise to tackle high-impact, performance-critical work across a large codebase. You will profile, diagnose, and optimize bottlenecks, mentor colleagues, and drive performance initiatives across distributed teams.

The role emphasizes measurement-driven problem solving, cross-team collaboration, and delivering tangible speedups that benefit millions of users of the Open Web.

Qualifications

• BS/MS in CS or CE with 5+ years of relevant experience.
• Proficient in C++ and performance-critical software.
• Experience with profiling tools (e.g., VTune, Xperf).
• Experience with multithreading, concurrency, or GPU work.
• Strong debugging and performance-bottleneck analysis skills.
• Ability to drive projects to completion with cross-team collaboration.

Responsibilities

• Write code and tests, build prototypes, profile and analyze performance bottlenecks.
• Learn about a wide variety of problems across a large, complex codebase.
• Educate engineers on performance through reviews, talks, tooling, and documentation.
• Break down complex performance problems into actionable steps and drive them to completion.
• Partner with engineering teams to support performance efforts and lead them within your area.
• Contribute to direction of performance benchmarks and prioritize impactful improvements.
• Work with team members to help bring the Open Web to millions of people

Skills

C++

Performance profiling

Multithreading

Debugging

Distributed teams

Asynchronous communication

Code reviews

Education

BS/MS in CS or CE

Tools

VTune

Xperf

Job description

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:

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
• 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
• 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++
• 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 team (which requires good asynchronous written communication skills as well as good verbal communication skills)

Bonus points if you have any of the following:

• Familiarity with Web Standards or patterns
• Familiarity with Android or Windows OS application programming
• A solid understanding of statistics

We value a variety of voices on the Performance Team and at Mozilla. You don’t need to check every box on this list to apply.

What you’ll get:

• Generous performance-based bonus plans to all eligible employees - we share in our success as one team
• Rich medical, dental, and vision coverage
• Generous retirement contributions with 100% immediate vesting (regardless of whether you contribute)
• Quarterly all-company wellness days where everyone takes a pause together
• Country specific holidays plus a day off for your birthday
• One-time home office stipend
• Quarterly well-being stipend
• Considerable paid parental leave
• Employee referral bonus program
• Other benefits (life/AD&D, disability, EAP, etc. - varies by country)

About Mozilla

Mozilla exists to build the Internet as a public resource accessible to all because we believe that open and free is better than closed and controlled. When you work at Mozilla, you give yourself a chance to make a difference in the lives of Web users everywhere. And you give us a chance to make a difference in your life every single day. Join us to work on the Web as the platform and help create more opportunity and innovation for everyone online.

Commitment to diversity, equity, inclusion, and belonging

Mozilla understands that valuing diverse creative practices and forms of knowledge are crucial to and enrich the company’s core mission. We encourage applications from everyone, including members of all equity-seeking communities, such as (but certainly not limited to) women, racialized and Indigenous persons, persons with disabilities, persons of all sexual orientations, gender identities, and expressions.

We will ensure that qualified individuals with disabilities are provided reasonable accommodations to participate in the job application or interview process, to perform essential job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us at [e-mail] to request accommodation.

We are an equal opportunity employer. We do not discriminate on the basis of race (including hairstyle and texture), religion (including religious grooming and dress practices), gender, gender identity, gender expression, color, national origin, pregnancy, ancestry, domestic partner status, disability, sexual orientation, age, genetic predisposition, medical condition, marital status, citizenship status, military or veteran status, or any other basis covered by applicable laws. Mozilla will not tolerate discrimination or harassment based on any of these characteristics or any other unlawful behavior, conduct, or purpose.