Maybe it's just a warped first impression, but Google Instant seems to do way more than we ordinary humans want it to do. As you search for something, it starts showing search results by predicting what you're looking for.
One obvious problem with this system is that, if your search is based on something you see in your last search results, Google Instant throws out those earlier results before you're done typing out the new search.
You might see a name, a date or a street address in one list of search results, and then try to narrow your Google search using that information. But because Google Instant pulls the rug out while you type, you have to delete the words you haven't finished and go back to remind yourself of exact spellings or specific numbers. Yes, you could copy and paste from the first search results, but sometimes you just want to type your search words and move on.
Instant disabler? I'm surprised Google did not anticipate this problem and give us a Google Instant disabling button. Or have they?