Hi,
JCH - Optimize is doing exactly what GZIP within Template is doing:. Combining and Compressing the CSS and JS files.
So, no need to use both of them (after your development period is ended). JCH is pretty powerful plugin, so you can keep using it. You won't need to enable the GZIP within the Template Settings. It won't be necessary. (otherwise, your website will try to compressed the already compressed files, which will cause extra processing load without any performance improvement)
If you like LightMart and satisfied with the support you have received, please "write a review" on:
www.flexiblewebdesign.com/Joomla-Virtuemart-Templates/LightMart
Rate LightMart and write a couple of sentences to share your experience with the support team.
It won't take more than 2 minutes from you but it is extremely important for us.
Thanks in advance!
Regards,
Support