Think you can help?

i don't know much about gaming except that i would turn off all the fancy effects and see how many fps i would get, then turn only the ones that didn't degrade the performance much.

That's because there are an overwhelming amount of polygons (compared to inside) displayed at one time because outside is big (to put in lamens terms) Inside, it is not as big a space. Therefore, there are less polygons to display. It happens in almost every game that is considered "high end" for your processor.