Site extremely slow

I am re-designing my web site and I installed the Joomla 2.5 and the template within a new folder. I am transferring the articles from the current web site and editing most of them. But the template is extremely slow. It takes 20 - 30 sec to access and after editing I can't save. It doesn't happens all the time but often having this problem. I asked hosting company and they said everything seems normal. Any suggestion?

Hi,

But the template is extremely slow.

is our demo page is also slow, I don't think so.
Did you enabled gzip and ..
please check using it : http://tools.pingdom.com/fpt/
- it will show you which element(s) makes horrible delays.

Thank you so much!