I use IGO 8 and it doesn't load all of the maps by default, it loads them as needed, like when you type in a state with it's address or you cross state lines. This is the best way to make GPS software IMO unless you just have an abudance of ram. This mod isn't going to make the program any faster nor save you ram, BUT there *IS* a benefit to being tidy and neatly tucking away the states you don't need. If you tuck them away, they wont' be in your way to select the states you actually DO need. 
Go into your igo8/content/map directory... create a new folder.. and move all the maps you
rarely need (once a year) there. Thus you eliminate them from the drop down choice menu
for your day to day selection, instead of having to scroll through multiple menu screens of
states you dont' need to get ot the ones that's physically closer but not alphabetically.
For instance, I on a daily basis live in a tri-state area, but i also go down the east coast once a year..
so I put all those states outside of the tri-state area in the new folder to pull them back up later
for that out of area trip.. but now on a daily basis when i need to change states, there's
the only 3 I have right in the menu and no scrolling through useless states.
That's a time saver and annoyance saver.
(haven't tried poi files but i'm guessing you may as well leave them in the map folder because
there's no reason for them to show you that file in the state selection menu).
If this already a posted subject, sorry i didnt' do a search, beat me with Hot metal soup spoon
and make me watch rosie.