There are plenty of complaints out there about Bluehost's CPU limits. I believe they just lowered it within the past few months, which has apparently made it too easy to max out.
Total coincidence, I'm sure... but I believe they now offer a more expensive plan that gives you the CPU usage you should be getting with the regular plan.
My guess is that it's a marketing gimmick to trick people into thinking they have a great high-traffic site that needs their more powerful plan... even though it would run fine on just about any other host. But that's just a guess.
Anyway, I'm not familiar with the setup you're using, but that doesn't sound like anything Dreamhost can't handle. There are plenty of people here using a bulky CMS or bloated forum software and they seem to be doing okay.
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