My team optimize Shopify sites every day (speedboostr.com) and can get you dialed in.
Resizing images is a good tactic to serve up the correct images depending on the user's viewport. You can use the html srcset attribute to control that.
If you need help from a developer feel free to reach out at speedboostr.com/contact. You can request a free analysis too if you'd like.
If you prefer to optimize in-house, you can use our free analysis tool the Shopify Analyzer. That will let you know what can and should be optimized on a Shopify site, plus a performance score (based on data from over 1,000 Shopify sites we've optimized).
Jay from Oakleaf Infoway. It was a pleasure to talking with you over the call, please check your email and let me know if you have any queries.
I found that your website has a lot of images so, to improve your website speed, you need to optimize your images.
Also, We've prepared for you this article: 13 Best ways to boost your Shopify speed.
Hope it helps!