Some of wordpress blogs consumes more resources(extreme MySQL usage} according to my host. Moving to VPS solves this issues? any idea?
The site will use the same amount of memory regardless of where it is hosted. A VPS would help to solve this a little bit because you would have your own RAM limit.
you might want to do a repair on your MySqL tables - if something is out of wack causing the high CPU usage, that might help.
I agree with grk519. There are limitations in shared hosting and you can get rid from them if you host your sites in a VPS. This is how high resource use of your site will not affect other sites.
If you have PHPMyadmin, you should be able to easily go in, select your database, put a checkmark in all your tables, and select "repair".
Try installing 1 Blog Cacher. Its a plugin for wordpress that caches your posts and reduces the use of your MySQL database. This could solve your problem.