PS3 and Xbox 360 only have 512MB of RAM vs the 8GB available to Xbox One and PS4. The tabulated vault idea that people keep throwing out would be great if the vault data was stored locally on your HDD, but it's not, it's on the servers. When you access your vault that data table is downloaded from the server in its entirety and cached into RAM as opposed to being read directly from the HDD. Every time you switch tabs, you will need to empty the cache from RAM and fetch the new data from the server and this generates more network and server traffic.