The speed of SVG as a graphics format depends greatly on the viewer and what kinds of changes you are making. I'm working on a project to measure some of the current viewers to determine reasonable estimates of what update rate they can maintain.

I have run non-trivial SVG applications driven by scripting on the order of 30-50 updates per second on multiple viewers.

Unfortunately, the feasibility of using SVG for this is a function of what update frequency you need and the complexity of your display (mostly the dynamic parts).