WordPress Site Optimization

I need my WordPress website optimized for both desktop and mobile devices. The key areas of focus are:

- Page Load Speed: Enhance loading times to improve user experience.
- User Interface: Revamp the interface for a more intuitive navigation.
- SEO: Improve search engine rankings using the current SEO plugin.

Currently, I'm using an SEO plugin and a page builder. It's essential that the optimization works seamlessly with these tools.

The mobile optimization should be targeted at both smartphones and tablets.

Ideal skills and experience:
- Proven track record in WordPress optimization
- Expertise in SEO
- Strong understanding of user interface design
- Familiarity with popular WordPress SEO plugins and page builders

Please provide examples of previous work and a brief plan of action.