I’m not the greatest expert in Wordpress here, but the way you phrase the question has too many possible answers all correct, and possibly contradicting each other. Speed of a website are influenced by too many variables
As a general reference, if you’re unhappy with any hosting provider, talk to the customer support first as they may give you specific insights about your situation. Your site may be not functioning properly because, for example, the wordpress installation has some rogue plugin or theme that slows things down. Or the hosting provider has your site on old/non-performing hardware. Or there are networking issues between your provider and you, which slows things down.
That said, in general, Wordpress instances at DreamHost are highly regarded for speed and reliability. Have a look at our Wordpress hosting options https://www.dreamhost.com/hosting/wordpress/ and try it yourself: there is a 97 days money back guarantee if you’re not satisfied.