website running very slowly

I was hoping someone may be able to offer some help.
the website www.firesidefabrics.co.uk runs extremely slowly.
If I run a pagespeed then it says there is a server response of 1.5-4 seconds which is very slow.
It only happens with this particular site.

I have seo mega pack running along with the journal theme.
The issue only really seems to have developed since I added the journal theme, but, I also did a site update to the latest 1.5.x patch.

Are there any known issues or is there something common I should be looking into?
I disabled the cache system within the journal theme because if enabled the site runs so slowly that it often actually crashes.

you should read this about optimizing OC v.1.5.6 performance:
http://forum.opencart.com/viewtopic.php ... 37#p592237

Ernie
openshop.li