CI_DB_driver Bug?

You still just explained alternatives to the solution

I didn't explain "alternatives". I gave you the solution and explained why it is such.

the thing is, OK on production i'll disable pconnect and there wont be any queuing for visitor's queries. but on local i do need the speed for my work to be fast and i want to keep pconnect true

You need the speed? How much is the difference between using a persistent connection and a regular one?
Unless you're using a remote database (which in the case of WAMP is most likely not), the difference shouldn't be noticeable, let alone significant.

but i just don't want to see this damn warning, coz it does nothing and has no implications on my code

You want to ignore a problem ... I'm not helping you with that.

its a codeigniter behavior

No, it's a MySQL behavior. It has nothing to do with CodeIgniter.

and there should be a way to suppress only this warning and not all the warning level notices. its like telling this warning that "Thanks for notifying but don't remind me again, because you are damn irritating. :\"

This may sound condescending, but ... programming doesn't work that way.