rocknbil - 5:45 pm on Feb 18, 2011 (gmt 0)
While it's possible, I'd first check the resources - some shared hosting conditions can do this no matter what you do. If it's on a VPS, you should be able to monitor what's slowing it down.
Can you try temporarily disabling one resource or the other during slow times? That is, temporarily shut down Wordpress and see if other pages improve.
I doubt a single database would improve anything.