WordPress Speed Optimization and Error Fixing

My entire WordPress site is experiencing critical errors and severe speed issues. The site has Elementor PRO and several other plugins. The homepage, product/service pages, and blog pages are all affected.

I need a professional who can:
- Diagnose the critical error on the site
- Optimize the site for speed and performance
- Ensure the site is fully functional

Please note, I haven't installed or updated any plugins before the issue occurred. Ideal skills for this project include:
- Expert knowledge of WordPress and its plugins
- Experience with troubleshooting critical errors on WordPress
- Proficient in speed optimization techniques for WordPress
- Familiarity with Elementor PRO

Your timely assistance in fixing these issues is greatly appreciated.