Is changing a level important in any way?

Hi, I was wondering If changing a level is important in any way. IE, performance, texture streaming, Flow.

My game is basically just one big level so far. Im just a little concerned that this may be a problem?

There are somethings you can do on an open map concept. The biggest IMO is properly setting LODs. I generally go with 3 LODs it basically reduces the nber of visible polys on an object based on distance. So stuff way off will have a very low LOD and as you get closer it changes to a higher level to show more detail. Look in the documentation for more info.