Wp Ecommerce SLowing down website

Plenty of sites run fine. Just done a check on one of my customer sites. According to webpagetest.org, start render in 1.6 seconds and document complete in less than four. Not the fastest on the planet but good enough. He carries thousands of items and makes a good living out of it.

Have you tried a cache plugin? Is it the actual page generation that takes time? Does your host have a decent sized query cache enabled?

If you post the URL we could provide more accurate feedback.