If you install J2store on a fresh Joomla and turn on debug option, you can see that J2store run about 17 database queries for a single product! It shows that this extension is not very optimized and needs premium host.
So what's the solution?
Hopefully J2store has a separate cache plugin and you can turn it on. to do that follow these steps :
1 Go to plugin list and turn off the joomla page cache plugin to avoid any conflict and then turn J2page Cache plugin on
2 Go to minicard module and in [Advanced] tab set Caching to No caching.
3 In Final step, go to Joomla global configuration and in [System] tab set System Cache on Conservative.
Now second opening of each page should be faster.
If you are familiar with a commercial cache extension share your experience with us.