Website score bad on google insights custom site in asp.net

The Issue [login to view URL] Prior to the latest Google insights update ( which now uses lighthouse to analyse the site ) we had managed to get our google insights score on both mobile and desktop to a fast or average speed. After the update the speeds have dropped to slow. Site history - The site was built approx. 10 years ago in [login to view URL] - with a CMS system - last year we kept the site but another developer made it responsive and added a few features and tweaks. 90% of the site is the same 2 pages - using the same layout but using different text and images. We have a homepage, studio page, contact page How our site works This is our home page - you can see here the way the site currently works is we design our own images/buttons for the page in illustrator or photoshop and then exporting the image as a JPEG. We then add these into the site using the CMS Editor We add both a mobile and a desktop JPEG and by double clicking the image we add a style sheet class Mobile-only or desktop-only We then hyperlink the image to the respective page or in the case of the buy now buttons we add the URL for the item we want it to be connected to. For the text we click source then add the code <div class="mobile-only"> to make the text mobile or desktop only. This is how the bulk of the site works we have various pages - however they all work in this manner - the only key difference is the content We have the home page [login to view URL] Overview page - [login to view URL] Product page [login to view URL] Studio Page ( This uses more embedded youtube videos than images ) [login to view URL] Something to consider is that on the site we have a carousel and banners that take you to the different pages The images in these seem to show on insights - and they may also be causing issues This only appears on the overview pages They both appear on the product page Job List We would like to improve our insights score, with particular focus on the mobile score 1 - Images Some images are being flagged as incorrectly sized We know that the background images that are showing on google insights are only meant for desktop - not mobile - (however before the lighthouse update they didn’t show on insights) these images need scaling down 2 - Below you can see the results for the mobile version of the homepage [login to view URL] We need the score bringing up here - it seems the best way to do this is to fix these issues - and as previously stated we have tried correcting images/text and no improvements seem to be made We would need this doing for the pages across the site, both our desktop and mobile sites - however I explained above the pages themselves are all made in the same manner and have very few differences between them so the changes should be the same. I believe on of the main issues may be the manner in which the images load, As I was visiting the site on my phone all text loaded way before the the images