System performance dosen't reflect just ram. Some applications will cause your performance percentage to drop depending on what your running. A screensaver for example can do the same thing. Try running an application as simple as a download and let a screensaver pop up and see what happens. It kills your system performance. I personally wouldn't worry about something that simple, when your performance drops like that the application running just requires more resources than other programs. The affect on RAM should not be that bad.
Hope that helped alittle.
Hope that helped alittle.