I have mine set at the default. It takes longer (for me) to load a large screen. This way I can quickly observe different areas on the map.
What does it matter, sure it loads faster, but if you have a big area of influence, then you have to keep changing the map, thus resulting in the same amount of time, if not more.
It's more of the lag that occurs when scrolling within the dimension view and the amount of memory consumed at once. A smaller dimension view reduces the lag and delay in scrolling and doing everything.