Magento mysql prcocessing at max causing site to time out

I have a main store with 25 sub domains with about 20k products in main store and looking at adding more in the coming weeks, because of the load site is timing out and pages are barely loading. My hosting company has supplied the information below. This is a problem with the way that Magento is configured or coded on your online store. As I pointed out previously, a single webpage is doing around 20,000 mysql calls. This is orders of magnitude too many. When we try and reindex, catalog url re write is stuck in processing. It is still the amount of processing that the site is doing on each page load. The number of mysql calls has not been reduced at all. These must get fixed properly to receive full payment of bid amount. Good communication a must and must be available via Skype, only experience with this kind of problem is preferred as time is of the essence.