Google search has a new feature called “Instant Preview” which pre-fetches search results pages and displays them in a preview pane when you hover over a search result. I suppose it could be argued that this is helpful, but many (including me) find it irritating.
To toggle instant previews on or off, all you have to do is click anywhere on a search result snippet (or click once on the blue magnifying glass). That will prevent instant previews from automatically popping up, or re-enable them if you had turned them off.
Somehow a lot of mainstream sites seem to recommend using adblock, greasemonkey or other plugins — but they’re not needed just for disabling instant previews.