Why is my site Slower than Slow?

I hate to bring up this subject again but my site is getting slower by the hour.

I am using WP Multi-site with 10 subsites. BP is on the main site.

My host (hostmonster.com) techs tell me the slowness is in my site and not in other sites on my server. They say my site is “throttling.” They showed me where I can download a list of slow queries, which I did. I deleted most of them and left others for the attached PDFs.

Some of the highlights are: Domain mapping is taking several seconds. Some queries take up to 17 seconds. Many queries are more than 6 seconds. In admin, when I click on a menu like plugins, it takes about 10 minutes before I see the page loaded. I installed Super Cache in Easy mode. It made no perceptible difference.

My key domain is http://edberry.com My two key subdomains are http://polymontana.com and http://climateclash.com. My customers are leaving because no one can use my sites.

Thanks for any help, Ed