Tools > Options > down to Infrastructure > Product Infrastructure
The first tab on the top left of the row is Cache Management. Right at the top of that page is a toggle to "Work with the cache system". Turn that on, and make your maximum size larger than 500MB. I've got mine set to 75% of RAM right now, and everything's working OK. You'll have to restart the session. What this will do, when opening a product, V5 will load CGR files instead of all those complete models. When you want to work on a part, double click it and it will load complete into the session. Expand the component, and double click the part level(the very top) of the next indention. Now you'll be working in the part like normal.
If you have any curve geometry that remains displayed on one or more parts, the curves will not show until you load the component, just a product of the CGR creation. This will lower your memory usage because all the components are only shown as cheap graphic representations, instead of full fledged solid models.
