Most of your questions don't apply to the system described in this article. You do not clone the repository, you merely chdir into a vfs that is backed by a co

Most of your questions don't apply to the system described in this article. You do not clone the repository, you merely chdir into a vfs that is backed by a consistent view of the repository at a point in time, which view is served from a large distributed service that lives in Google datacenters alongside other Google services like Search, Maps, and Gmail. Because it is enormous and nobody clones it, it is also true that nobody partially clones it. You do not "checkout a subfolder" either. Your last point is the only one that applies. If you want your view to advance from revision 123 to revision 125 it takes about a second to do so. If you have pending (not yet submitted) changes in your client, they might have to be merged with other changes, which can take a bit longer. If you have a really huge pending change, and your client is way behind HEAD, it might take a few tens of seconds to merge everything.