This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Staff Fullstack Software Engineer, Core Performance based in Canada. This is a high-impact, organization-defining technical leadership role focused on making large-scale consumer products feel fast, responsive, and reliable across every user surface. You will own performance across web, mobile, desktop, and backend systems, shaping how hundreds of millions of users experience the product. The role begins with deep hands-on work in the web stack, where you will profile high-traffic React surfaces, analyze performance bottlenecks, and deliver measurable improvements. Beyond the web, you will define and coordinate performance strategy across iOS, Android, and desktop in partnership with platform teams. You will also build the measurement and observability systems that enable performance engineering at scale across the organization. This is a rare opportunity to define an entirely new discipline, set engineering standards, and influence technical direction at an org-wide level. The environment is highly technical, data-driven, and focused on building systems that directly translate into product and business impact. \n

Accountabilities: Own and drive end-to-end performance improvements for the web application as the initial focus, including profiling React-based surfaces, generating flame graphs and heat maps, and shipping measurable optimizations. Lead performance strategy across iOS, Android, and desktop by coordinating with platform engineering teams and defining shared measurement and optimization standards. Identify, analyze, and resolve performance bottlenecks across the full stack, from frontend applications to backend services in Python and Go. Design, build, and maintain performance measurement, telemetry, and regression detection systems used across Core Engineering. Translate performance insights into production-ready code changes and validate impact through real-world telemetry and experimentation. Define engineering best practices, standards, and frameworks for performance optimization across multiple teams and surfaces. Mentor senior engineers on profiling techniques, system design for performance, and data-driven optimization methodologies. Drive cross-functional alignment with engineering, product, and design leadership to ensure performance is treated as a core product priority. Apply and scale AI-assisted engineering workflows to accelerate performance analysis, debugging, and optimization across the organization. Requirements: 12+ years of software engineering experience, including significant senior or staff-level technical leadership responsibilities. Strong hands-on experience improving performance in production consumer applications, particularly web-based systems using JavaScript and React. Proven expertise in performance profiling techniques, including flame graphs, traces, RUM data analysis, and root-cause debugging. Experience delivering measurable improvements that directly impact customer-facing performance metrics. Strong backend engineering experience in Python and/or Go within production-scale systems. Demonstrated ability to lead cross-org technical initiatives spanning multiple teams, surfaces, or platforms. Experience defining engineering standards, architecture decisions, and measurement frameworks at scale. Hands-on experience using AI tools to accelerate software engineering workflows, particularly in debugging, refactoring, or optimization tasks. Experience improving or scaling AI-assisted engineering productivity practices across teams. Excellent communication skills with a track record of influencing technical direction beyond direct reporting lines. Experience working on consumer-facing products with direct impact on user experience metrics. Benefits: Competitive compensation ranging from $204,900 to $277,200 CAD annually. Opportunity to define and lead an org-wide performance engineering discipline from the ground up. High-impact role influencing product experience for hundreds of millions of users. Flexible, remote-friendly work environment within Canada. Exposure to senior leadership and strategic technical decision-making. Opportunity to shape engineering standards, tooling, and performance culture across a large organization. Work on complex, large-scale systems spanning web, mobile, desktop, and backend infrastructure. Strong technical growth in a highly advanced, data-driven engineering environment.

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