Website hosting – Bluehost/Layeredtech/Rackspace

My blue host server has become a sluggish lately. The CPU throttling is on more than not and sometimes the webpages take a long time to load or I even get a ‚Äúdatabase unavailable” error. My http://macintoshhowto.com site is getting 150K visits a month, http://dubbo.org gets 20K visits monthly and