The current world models include some very large textures, which is why the posters and app's look so good when you are close to them. On the downside this consumes a fair amount of memory, and is especially hard on the graphics card memory.
For the demo at JavaOne, ie the current world content, the focus is on a world that looks really nice. After the show I'm planning some work that will make the textures dynamic, showing low resolution versions when the user is far away and increasing the resolution as they get nearer. This should help significantly with performance especially when texture heavy areas such as the team room are in view.
Out of curiosity I'd like to hear from everyone else on what hardware you are using and your perception of the current performance.
I'm using 2 machines
Toshiba Terca M2, GeForce 5200 Go, 1.5GB ram (large ram for developer tools)
Runs fine with existing world, adding any more large textures however makes performance
Desktop, 3.2Ghz, Nvidia 6800, 1GB ram