React & Nodejs code review and & Architecture Review

We have an existing React + Node.js web application that has grown significantly over time and is now experiencing performance issues, increasing technical debt, and deployment instability. We're looking for a Senior Full Stack Engineer or Technical Lead with proven experience rescuing and modernizing production applications. Your primary responsibility is to perform a comprehensive technical audit, identify the root causes of our issues, and provide a practical roadmap for stabilizing and scaling the application without disrupting production. This is an architecture and diagnostics engagement not a feature development project. Current Challenges Performance bottlenecks impacting user experience Frequent bugs introduced during deployments Growing technical debt slowing development Difficulty scaling the application Complex and potentially inefficient database queries Frontend rendering and state management issues Lack of a clear long-term architecture strategy Scope of Work You will perform a comprehensive review of our application, including: Backend Review Node.js architecture and application structure Identify event loop blocking and performance bottlenecks Analyze API performance and request lifecycle Review database schema, indexing, and query efficiency Evaluate caching strategy and scalability Identify memory leaks or resource utilization issues Frontend Review React architecture and component structure Analyze rendering performance and unnecessary re-renders Review state management approach Evaluate bundle size and loading performance Identify maintainability and scalability concerns Architecture Review Assess overall system architecture Identify technical debt and high-risk areas Review deployment reliability and release process Recommend best practices for future development Deliverables Comprehensive Architecture Assessment Detailed report identifying critical architectural issues and technical debt. Performance Audit Root cause analysis of backend and frontend performance bottlenecks. Database query analysis and optimization recommendations. Deployment and scalability assessment. Prioritized Refactoring Roadmap Step-by-step implementation plan. Prioritized recommendations based on business impact and effort. Suggested quick wins and long-term improvements. Risk assessment and migration strategy. We're looking for someone who has: Expert-level experience with React and Node.js Strong understanding of scalable web application architecture Experience auditing large production codebases Proven track record rescuing legacy or high-technical-debt applications Deep knowledge of performance profiling and optimization Experience with database optimization (SQL and/or NoSQL | MongoDb) Excellent communication skills and the ability to explain complex technical concepts clearly Proposal Requirements Please include: A brief overview of similar codebase audits or modernization projects you've completed. Examples of performance or scalability issues you've successfully resolved. Your approach to conducting a technical audit. Estimated timeline for completing the assessment. Any relevant architecture, performance, or technical leadership experience.