I'm running on a 56k dial-up here (yes, Virginia, some of us still do), and had no problem running these worlds. However, I was the only one in there so this is not a very good test. For those who want a low-cost/no-cost approach to building 3D chat worlds, ABNet is a good place to start and may prove to be a commercial survivor. The site describes the software thusly:
ABNet is a communication framework that happens to let you create 3D multi-user chat worlds. It isn't limited to this application but 3D chat shows its flexibility. The communication framework of ABNet provides an asynchronous low-latency publish and subscribe environment using XML messages.
The communication server of ABNet is written in Java allowing for deployment on any platform running a Java VM. The client side of ABNet uses Javascript on an HTML page to turn a single-user VRML or X3D world into a Multi-user Virtual World environment. 3D Avatars can interact and use shared events to provide a virtual experience much like the old blaxxun community platform. ABNet is the software that powers http://vrmlworld.net
ABNet can be used to build your own chat site that uses very little bandwidth. It is feasible to run a 3D chat site from your personal computer.
The software supports both the Contact 6.1 and MediaMachines browsers.
Some useful URLS:
Forums:
http://vrmlworld.net/forums/viewtopic.php?t=118
Setup the Software
http://vrmlworld.net/forums/viewtopic.php?t=105
Download the current ABNet 2 ActiveX client from here:
http://kimballsoftware.com/abnet/abnetclient2_002.exe
Download both the client and java server from here:
http://kimballsoftware.com/abnet/abnetserver2_002.exe