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Senior Software Engineer, Firefox Performance

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Mozilla

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Location:
Canada

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Category:
IT - Software Development

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Contract Type:
Not provided

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Salary:

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Job Description:

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.

Job Responsibility:

  • 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, mature codebase (ex: what can slow things down when you have old code talking to new code and what can we do about it?)
  • Use several programming languages (e.g., C++, JavaScript, Kotlin, Rust, Python) and techniques to fix performance issues, with an emphasis on C++
  • Help to educate engineers on other teams about writing more performant code through code reviews, giving talks, and/or writing documentation
  • Work with driven, committed team members to help bring the Open Web to millions of people

Requirements:

  • 5+ years experience as a software engineer
  • A solid understanding and strong working experience in C++
  • Experience developing performance critical software
  • Proven experience taking an experimental and measured approach to solving problems (measurement, and using experiments to diagnose an issue or prove out a solution)
  • Strong debugging skills in analyzing performance bottlenecks
  • An interest and ability to work in a distributed team (which requires good asynchronous written communication skills as well as good verbal communication skills)
  • Commitment to our values: Welcoming differences, Being relationship-minded, Practicing responsible participation, Having grit

Nice to have:

  • Experience with multithreading and concurrency, disk I/O, GPU, etc
  • Familiarity with Android or Windows OS application programming, profiling and debugging
What we offer:
  • 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)
  • Flexible work environment (majority of Mozillians work remotely)
  • Industry-leading paid parental leave (up to 26 weeks of fully paid leave for childbearing parents and up to 12 weeks for non-childbearing parents)
  • Reimbursement for professional development (up to $3,000/year)
  • A work setup including the latest hardware and software of your choice

Additional Information:

Job Posted:
January 02, 2026

Employment Type:
Fulltime
Work Type:
Remote work
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