Queues - Is Infinity all right?

[Anand Pillai]

The standard Python Queue module, allows to generate queues that
have no size limit, by passing the size argument as <= 0.

q = Queue(0)

In a multithreaded application, these queues could be useful
when you have many threads using the queue for data access
and synchronization.

Is there a performance hit when one uses an 'infinite' queue
when compared to a queue of fixed size? 

Of course it should depend upon the O(n) of the Queue data structure,
how the time of access (get/put) varies with the number of items in 
it. 

I would like to have some light on this. Is it constant, O(n) or
a higher order?

Thanks

-Anand