Right now knife vault refresh foo bar takes a long time if the search for foo/bar hits a lot of nodes (hundreds to about a thousand in my test).

From my analysis, this primarily comes from two sources:

• Downloading all the node objects take a long time. About two minutes on my test connection (hosted Chef, I'm in Europe on a DSL line). As we don't actually need the full node objects, we can use a partial search and just ask for the host name.
• Downloading the client keys is dominated massively by latency. I see two ways this can be solved: use threads or construct a big search query to download all the public keys in one go; basically doing .search(:client, "name:foo OR name:bar OR name:baz …).