Delphi application: find a small problem

I have a small demo application that does a screen captures and sends it to the the client. You can select the area of the screen you want to capture using a "form" that you can resize. Everything works ok but I have a problem with the frame rate, indeed when the "selection form" is minimized the frame rate drops on my PC by half about 9fps. When the selection form is displayed the fps is around 20. Your job is to find out why the frame rate drops and fix it so I get 20fps or more whatever selection frame is minimized or not, or hidden. I have attached the source of the server and the exe of the client. I use D2010, you need Overbyte ICS network components as well a zlib that i have included.