Senior Frontend Performance Engineer – React

iDelsoft

. Own frontend performance across the entire application, including startup time, interaction latency, scrolling, rendering, memory, and perceived performance .

Posted 11/9/2026full-timeRemoteSeniorWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates deep expertise in React and TypeScript, with a strong focus on frontend performance optimization, including rendering, caching, and data synchronization. Proven ability to build custom performance infrastructure and improve application performance in production environments.

Highest-signal resume keywords

React Application DevelopmentTypeScript ProficiencyFrontend Performance OptimizationCustom Infrastructure DevelopmentPerformance Benchmarking

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

JavaScript PerformanceMemory ManagementCaching TechniquesData SynchronizationState ManagementVirtualizationLazy LoadingAlgorithmsBrowser InternalsWebAssembly

Soft Skills

Attention to DetailCollaboration

Tools & Technologies

Profiling ToolsPerformance ToolingOpen-Source Frameworks

Industry Keywords

SaaS ApplicationsStartup ExperienceFast-Moving Product Company

Tech Stack

Tools & technologies

JavaScriptReactTypeScript

About the role

Key responsibilities & impact

Own frontend performance across the entire application, including startup time, interaction latency, scrolling, rendering, memory, and perceived performance
Design and implement advanced rendering, caching, preloading, and data synchronization systems
Build custom performance infrastructure where existing libraries and frameworks fall short
Profile and eliminate bottlenecks and UI jank using browser and application profiling tools
Work with feature teams to ensure new functionality maintains performance standards
Continuously benchmark the product against the fastest SaaS applications in the industry

Requirements

What you’ll need

4+ years of frontend engineering experience, including 4+ years building large-scale React applications used by thousands of users
Proven track record of significantly improving application performance in production
Deep expertise in React, TypeScript, browser internals, rendering, memory management, and JavaScript performance
Extensive experience with caching, virtualization, lazy loading, data synchronization, and state management
Experience building custom infrastructure or frameworks — not just wiring up existing libraries
Strong computer science fundamentals and algorithms; exceptional engineering standards and attention to detail
Experience on products where performance was a primary business objective
Experience with WebAssembly, workers, or other advanced browser performance techniques
Experience at a startup or fast-moving product company
Contributions to performance tooling or open-source frameworks