Google Instant Search

Multiple submissions on the same subject:

http://news.ycombinator.com/item?id=1672391

http://news.ycombinator.com/item?id=1672388 <- This is an explanation

http://news.ycombinator.com/item?id=1672346 <- This one, and it was first

There is something strange:

I typed "This is cra" and I saw a lot of results.

Then I completed with "This is crazy" and suddenly the search result is empty (asking to hit enter, after which the results are displayed)

It seems like the search results are displayed as you type only if the search phrase is recognized by search suggestion.

The completion suggested "this is crack and this is what you smoke it in" when I wrote that (without hitting enter) google rendered a result immediately.

So it seems that google is not simply executing the partial search as you type (it would be too expensive even for them), but it precomputes the search results for each the search suggestion. Does it make sense?