I'm using it on my laptop which has 6GB RAM, and 4267MB is in use. That's with Excel open, KeePass2, Thunderbird, and 13 Chrome tabs open. Never really got over 1.5GB used when using 8.1 before with this little open. As a matter of fact, I've had a whole lot more open and always had trouble getting the machine to utilize 4GB before (back when I was running a 16GB desktop on 8.1).
It's most likely because they haven't worked on the memory management as much yet, as they are still doing UI changes. Memory management should be in place by the time of the consumer release.