Staff Performance Engineer, Firefox

Mozilla

. Write code and tests, build prototypes, tackle problems, and profile and analyze performance bottlenecks .

Posted 10/9/2026full-timeRemote • United StatesLead💰 $139,000 - $218,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates deep proficiency in C++ and working proficiency in JavaScript, with a strong focus on developing performance-critical software. Capable of driving projects to completion while collaborating effectively with distributed teams and utilizing profiling tools to analyze performance bottlenecks.

Highest-signal resume keywords

C++JavaScriptPerformance-Critical Software DevelopmentDebugging and Analyzing Performance BottlenecksProfiling Tools

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

C++JavaScriptKotlinRustPythonMultithreadingConcurrencyDisk I/OGPU WorkPerformance Benchmarking

Soft Skills

Asynchronous CommunicationCollaborationProblem SolvingEducating Engineers

Tools & Technologies

VTuneXperf

Certifications & Qualifications

BS in Computer ScienceMS in Computer ScienceBS in Computer EngineeringMS in Computer Engineering

Industry Keywords

Performance OptimizationCode ReviewsTechnical RoadmapOpen Web

Tech Stack

Tools & technologies

JavaScriptKotlinPythonRustC++

About the role

Key responsibilities & impact

Write code and tests, build prototypes, tackle problems, and profile and analyze performance bottlenecks
Learn and solve problems across a large, complex, and evolving codebase
Use C++, JavaScript, Kotlin, Rust, and Python to fix performance issues, with emphasis on C++ and JavaScript
Educate engineers on other teams through code reviews, talks, tooling, and documentation
Break down complex performance problems into actionable next steps and drive them to completion
Partner with engineering teams across the organization to support and lead performance efforts
Contribute to performance benchmark direction and prioritize important improvements
Own browser performance for a significant area end to end and contribute to the Performance team's technical roadmap
Work with team members to bring the Open Web to millions of people

Requirements

What you’ll need

BS/MS in CS or CE, and 5+ years of relevant experience
Deep proficiency in C++
Working proficiency in JavaScript
Proven experience developing performance-critical software
Experimental and measured approach to solving problems using measurement and experiments
Proven skill in debugging and analyzing performance bottlenecks, and using profiling tools such as VTune and Xperf
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
Interest and ability to work in a distributed team, with strong asynchronous written and verbal communication skills

Benefits

Comp & perks

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)