Hi,
You should use the Joomla debug mode in order to understand what took some time in the page generation.
For what I saw also, is that you have some cache system ; because the first time the page load could be high but the next reloads are pretty fast ; so you should choose new pages when using the debug mode analyzer.
Regarding your product page, I think that the module which display random products could be the source.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.