Page Speed/ Correct Image Size (Mobile)

Hello all. I have created a site and the mobile page speed is absolutely horrible. I was hoping to get advice on ways to optimize mobile tag load speed, and learn about any suggestions the webflow community has for proper image sizing and format. The website I am having issues with is accident.com/injury/workers-comp.

What is the proper image format and size I should be using for our hero??
Are there any other ways to make page load speed faster??