I have owned ecommerce stores for the last 5 years and always worked on slowly improving quality and flow on my own. Cut to recently(April of this year) we launched the newest version of our site. This site took almost a year to build and contains around 100K products and growing. We sourced the best product data and images and spent so much time trying to make the site look beautiful and show our customers our full Catalog of products. Everything went great, but as you can guess from what I said about our data, the website was slow. Not the slowest out there but still not snappy like other sites. We looked around for a bit and tried a couple solutions on our own to improve site speed. They did help a little but nothing significant, and also not in a way that you could "feel", it just said on a screen that it was faster. A few weeks ago we got this product and did the DIY set up which did have a decent improvement to the site speed. However, they give you an option to take it a step further and have them implement some changes to your site code if you want to improve it even more. We set that up with them to do and just a week or so later they had time to work on implementing those changes. The first try was successful in making the site MUCH faster, but it also had so side effects that were causing some weird issues. We rolled back the theme to the previous unmolested version and then reached out to them explaining the few little issues we were having. The issue were nothing major but just little aesthetic stuff like the dropdowns on the site were all open and the reviews in the testimonial section were showing up on mobile in a weird way. They responded right away and said they would go back in and see what went wrong. Roughly 24 hours after the initial update to the code they fixed the couple issues on the optimized theme they had created. We launched it a few days ago and boy oh boy, it is MUCH faster! It is a little hard to tell because it has been a few weeks since I did the DIY stuff to improve speed and then after they did their thing it got even better, but I feel like if I never even saw that center stage and got used to it, then going from the original slow speed directly to the brand new much faster speed would have blown me away even more. All in all though I would say absolutely buy this at the highest tier if you can afford to do so. After reading many studies about how each second of load time dramatically increases bounce rate and decreases conversion rate I knew I had to something. I am very glad I found this app and I am very appreciative of them getting that install done in a timely and professional manor. I am also even more impressed that when I told them about a couple issues that they didn't pass blame or leave me hanging. They got back in there and got it fixed almost immediately. Absolutely would recommend this app and these people!!