[Ann in Arlington]

I did my standard search for "brillig" which has the advantage of being both a nonesense word and one that is found in only 4 items on my Kindle so all the results plus the number of unindexed items show on the first page. Since I have so many items on my Kindle, the search takes about 4 minutes.

I search for something like xqprz which isn't in any of the books. . .even with 700 titles the results come back pretty quick.

 

[Ann in Arlington]

I think it's because the search is a little bit smart and knows there aren't any real words that begin with two or three random consonants.  It would probably take longer, though if you searched schxgqz because there are words that begin sch. . . .  At least, that's my analysis, but who knows!