FFXIV window mode causing lag issues to other applications only when minimized.

Details:
I play FFXIV in window mode. It's size covers the whole screen.
I experience lag on other applications caused by FFXIV under certain conditions:

1) If I minimize the FFXIV window, other applications will lag.

2) If I maximize other applications (of example Internet Explorer), while FFXIV window mode is running in the background (not minimized), they will lag.

I do not experience any lag on my other applications if FFXIV window mode runs in the background (not minimized) & none of the other applications are maximized.

I can manually resize an Internet Explorer window to cover my whole screen and it won't have any lag unless I press the maximize button.

Frequency:
Always

PC Manufacturer & Model Number:
Homebuilt Computer

Operating System:
Windows 7 Home Premium

Graphics Card:
ATI Radeon HD 5700 series

Type of Internet Connection:
CATV

What's happening to your RAM and CPU usage when you experience this? Maybe that can clarify something to get an idea of the problem.

If I use FFXIV and a youtube video:

FFXIV running normally & youtube video in small window: CPU stable at 18%

FFXIV minimized & youtube video in small window: CPU between in peaks 24-27% , youtube video skips/lags.

FFXIV running normally & youtube video in maximized window: CPU between in peaks 24-27% , youtube video skips/lags.

sounds like your pc has too little RAM and pages ffxiv to your hdd once you maximize another program. Try looking at your HDD LED right after you maximize a program. If it starts blinking rapidly, wait till it stops and see if youtube will still continue to lag after that.

I have 6 GB RAM and I think not even 3GB was used when I tested it. I find it weird that the lag starts when the FFXIV becomes "hidden". I would have assumed, that considering FFXIV wouldn't have to draw anything out in that mode, that would have been even easier for the computer to handle, but it's not the case. The lag isn't temporary either: as long as FFXIV is minimized or has another window maximized over it, it will cause lag to other programs.

Games usually get drawn even when they are minimized. Do you have the newest drivers? Sounds like GPU process priority isn't handled properly.