Shopify Speed Optimization

I need someone to fix my Shopify speed without using any apps. The primary goal is to improve user experience.

Key Requirements:
- Optimize slow loading images
- Minimize heavy JavaScript files
- Reduce large CSS files

Ideal Skills and Experience:
- Expertise in Shopify development
- Strong knowledge of web performance optimization
- Experience in manual optimization without third-party apps

Please provide examples of similar work done.