Page always takes at least 30 seconds to load
It could be several things:


Views executing sql queries that have performance problems.
Cache problems (Do you have enabled the Drupal's cache?).
(If you have a VPS) maybe the server that you are sharing is under heavy load.
(If your site is integrated with web services) maybe the web service is having performance problems or connection problems.


Try to check the logs of the site to see is there are errors or anything that could be related to this problem.

Another alternative is to use a profiler like Xhprof (there is a module for drupal) or XDebug.

Could you share with us the url of the website?