Cooked or launch in editor only uses 1.2 gig?

Ive got a sample project, some static meshes etc. About 15 gig of assets, and a collection of streaming volumes. Everything works ok, and as is should when I run in launch in editor or when cooked, appart from the fact that it only uses just over 1 gig? Im wanting to cook and build for a 6 gig machine and load all assets into memory in the background while the player is playing. The reason im asking is level streaming takes AGES.
too long. and instead of being already resident in memory the assets try to load from disk, again and again, making things messy. Its an open world so i cant just load in a linear pipepline but its as and when player enters an area.
thanks in advance for all advice.
if i can ask a few questions on top? 1 are there settings in cook that let my specify, load all assets up to 4 gig ? is there a tickbox list of assets to set to aload and when. 2 do i work round things as a hack by setting always loaded to enough of my streaming levels, until i get to 4 gig and then stream the rest? how does one have more control over what loads and when?