Long wait time when starting POST uploads...

I've implemented an PHP based file transfer system for a division where I work. The purpose is to allow these users to trade huge files more simply. As such, I've noticed that when a user clicks submit on my initial form page, it is then supposed to popup a new window which loads a small html page that says essentially: "Your file xxxxxx is being uploaded, please wait.... <animated gif>", however, the initial delay between when the window opens and the page gets loaded into it seems quite large. Is this somehow due to the large filesize? I've noticed that a lot of diskgrinding occurs on the machine you're uploading off of when you first hit submit. Any ideas? Thanks in advance to any and all that reply. -- Tim Meader ACS GSG tmeader@cne-odin.gsfc.nasa.gov