React.js App Fix & Enhancement

I need an experienced React.js developer to fix and improve my app.

The app currently suffers from several issues:
- UI/UX problems: The interface is not user-friendly.
- Performance issues: The app is slow and unresponsive.
- Functional bugs: There are several errors affecting functionality.

Your improvements should focus on:
- Enhanced user experience
- Increased performance
- New features

Ideal Candidate Should Have:
- Proficiency in React.js
- Strong UI/UX design skills
- Experience with app performance optimization
- Solid debugging skills to fix functional bugs
- Ability to implement new, scalable features to enhance the app's workflow

Please provide examples of past work, especially projects that required similar fixes and enhancements.