If you want a fast site, fix your images. Rename files to be descriptive...

https://rapid-wiki.win/index.php/How_to_Master_Image_SEO_Without_Falling_Into_the_Keyword_Stuffing_Trap

If you want a fast site, fix your images. Rename files to be descriptive instead of using generic tags like "IMG_001." Write alt text that actually helps users and search engines understand the context