Senior Staff Performance Engineer, Firefox

Mozilla; Toronto; On-site; CAD 165,000 - 220,000; Full time

Benefits offered by this job

Generous bonus plans

Medical, dental, and vision coverage

Retirement contributions with vesting

Home office stipend

Professional development budget

Parental leave

Employee referral bonus

Well-being stipend

Life/AD&D, disability, EAP

Job summary

Mozilla seeks an experienced performance engineer to optimize the Firefox browser across Windows, Android, Linux, and macOS. You will tackle bottlenecks, write fast code, and collaborate with distributed teams to improve overall speed and reliability for users.

Expect to work with C++, JavaScript, and profiling tools, contributing to performance strategies and education across teams. This role is based in Canada with a strong focus on browser performance.

Qualifications

• BS/MS in CS/CE with 7+ years of relevant experience.
• Mastered understanding of C++ and proficiency in JavaScript.
• Proven experience in performance critical software and profiling.

Responsibilities

• Write code and tests, build prototypes, and profile bottlenecks.
• Learn across a large, evolving codebase and complex problems.
• Use C++, JavaScript, Kotlin, Rust, Python to fix performance issues.
• Educate engineers through reviews, talks, tooling, and docs.
• Define and drive actionable next steps from high level objectives.
• Collaborate with teams to lead performance efforts.
• Shape future performance benchmarks and improvements.

Skills

C++ proficiency

JavaScript proficiency

Performance profiling

Multithreading

Distributed systems

Debugging skills

Asynchronous communication

Education

BS/MS in CS/CE

Tools

VTune

Xperf

Profilers

Job description

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
• Independently define and drive actionable next steps from high level objectives
• Work with engineering teams across the organization to assist and lead performance efforts
• Shape the future of performance benchmarks, and set the proper priorities for the necessary improvements
• Develop strategies for the future of the Performance team and the Organization as a whole
• Work with driven, committed team members to help bring the Open Web to millions of people

What you'll bring:

• BS/MS in CS, CE and 7+ years relevant experience
• A mastered understanding of programming in C++
• An understanding of programming 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 multithreading and concurrency, disk I/O, GPU
• Proven track record of setting team goals and driving them to completion.
• Experience motivating and aligning cross-functional teams to deliver on 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
• Prior experience working on a modern web browser

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
• Annual professional development budget
• 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.

Hiring Ranges

Canada Tier 1 Locations

$165,000—$220,000 CAD

Canada Tier 2 Locations

$149,000—$199,000 CAD