Yes. It may be a little slow when it first starts up because it's trying to check the web for the latest config, but you can disable that by going to the Update screen (the bottom link on the left pane takes you there) and unchecking the always check for updates box.
When you click on the more info article links, that may slow as well because it looks on the web, but it will then fall back to local help and get the articles from there. If it hits three failures in a row, it will stop trying for ten tries, then try again (we really want to access the web articles because then we can get statistics on how much each article is accessed).
This information is all in the FAQ, by the way.