For an eCommerce site, it’s imperative for your site to be fast, although it could be argued that the more niche your product is, the less important it is.
Site looks good and clean and is delivered through https which is great. The only nit I would pick is that it’s not an html 5 template.
For the implementation, if possible, can you enable keep-alive? That’ll lower the overhead of the site. The TTFB is low, so there’s not much that’s going wrong server side ( well, you should also check with your FPC disabled as well as that can make a huge difference ).
So next thing to look at is delivery. If you can use http2, then that will aide in performance by re-using connections to their fullest so none of the connection overhead. If this is not possible, then you need to look at reducing the resource count. look for something that merges the css and js files… js often breaks when you do this, but you normally get away with css. In addition, using a lazy loader to only show resources on the screen will also help with the perceived speed - I’ve found BJ Lazy Load to be a no brainer for this for years.