I'm looking for a good JavaScript tree / treegrid package. Now -- before you answer:

It needs to be able to perform well with lots of nodes. Perhaps 1,000 sibling nodes. It needs to be able to draw to a usable state within 2 or 3 seconds with 1,000 nodes. It doesn't necessarily need to draw all 1,000 nodes at once -- if it supports some sort of "smart rendering" or fake scrolling.

Beyond that, column resizing, drag and drop, inline editing would all be nice, although I could probably add that functionality myself.

I've already tried dojo's tree and yahoo's YUI treeview. Both are too slow.