DreamHost did have some speed issues recently, with many reporting their sites were slow. The issue was traced to an internal DreamHost router that wasn't performing up to specs. I believe this has now been rectified.
Check out the sites at the link below for examples of how DreamHost hosted sites currently perform.
Is that 10,000 visitors per day, or per month?
If those are daily figures, then you are really going to be pushing the limits of any shared hosting and you would be best advised to obtain a dedicated server for your site.
Of-course, this does cost more, but a site with that much traffic should be able to cover the costs easily.
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