Why am I getting "Waiting for my_site_name"????

[John Hudak <jjhudak@xxxxxxxxx>]

Hi:
I am running Apache 2 under Ubuntu server 8.04.  I have configured and set up two virtual web sites.  One web site set of pages is located in the 'default' apache document source.  The other website is located in a directory that I have set up in a user directory. (I did an add user and gave the user name the name of the website)
The virtual hosting is on one IP address, and I am doing virtual name hosting.  I am going through dyndns host mapping that will redirect http requests for name 'A' to my internal LAN, and my router port forwards HTTP requests to my local server address. Similarly for site 'B'   Both sites seem to work well when there is no load.  When site 'A' is being accessed, if I concurrently do another HTTP request to 'A', the connection is made, then I see "Waiting for my_site_name".....for a long time, until (I guess) a time out occurs and my request is flushed.  Site A serves a number of pictures, that on the average, can take aboug 20-25 seconds to serve up. (Yea, my isp really throttles down the speed...).  Could the picture serving be the cause?
If I access site B concurrently while site A is being accessed, I see no delay.  I would think, even if  A is serving up pictures over a slow link, Apache is multithreaded and should handle requests for other pages, so why the "Waiting for 'A'" state?

Could someone suggest where the bottle neck might be and how to fix it?  Is there anyway to monitor the server to see where things are being blocked??

Much thanks for any help.
-John