Accessing the same php file buy multiple users

I have the following situation.
Im using a dispatcher to handle the different states that a user can be in while in my site.

I ran into something earlier that concerned me a bit.

Say I have the dispatcher that looks something like this : (lots of psudo code here)

class Dispatcher extends Orig_Dispatcher
{
public function __construct($helperObjects, $request)
{
...do stuff here
}

public function dispatch()
{
$func = $this->getRequest();
$this->$func();
}

public function display()
{
require_once ('display_stuff..php');
}

public function doSomeThingElse()
{
require_once ('somethingelse..php');
}
}


The url looks like this :
example.com/?state=display


If someone accesses that display fuction and that DB qry happens to take long time - then at the same time someone else trys to access that doSomeThingElse function - nothing happens until that display function by the different user finishes.
I even replaced the DB stuff w/ a sleep 60 and got the same results.

This is the first time Ive ran into this - but is this an accessibility issue w/ PHP?
Any help or suggestions at all would be great.

Thanks
-Rob