Hi,
As far as I can see on your website, it loads as fast on HikaShop pages than on pages where HikaShop doesn't display. So it doesn't look like a problem of HikaShop at all.
You need to tweak the performances of your whole website/web server.
There are plenty of solutions for that.
For example:
- joomla pages caching plugins
- APC
- gzip compression
- joomla plugins for js/css minification/caching
- increase your hosting resources in order to process the pages faster
- use a CDN in order to provide your CSS/JS/images faster to your users
www.siteground.com/tutorials/joomla/joomla-speed.htm
www.ostraining.com/blog/joomla/joomla-tu...-using-jch-optimize/
Note that some caching options might actually cause issues with HikaShop elements like the cart as the pages need to display different things for different users. But even just having APC on your web server can already help a lot and won't break anything.