"Finally i haven t done much with animation but i think you re entirely correct - d3.js provides more animation support than protovis especially in terms of animated transitions"
from question "Protovis vs D3.js"
"For semantic zooming you ll notice that d3.js is significantly faster than protovis"
from question "Fast and responsive interactive charts/graphs: SVG, Canvas, other?"
"The team behind protovis has since created d3.js so this is likely a better option than protovis"