If you're interested in slow queries, try the one below (via [1]):

    the OR google OR a OR "supercalifragilisticexpialidocious" -the -google -a

You can replace the "supercalifragilisticexpialidocious" term with something unique if the results end up cached. This takes upwards of 5 seconds to return back.

[1] https://www.quora.com/What-is-the-slowest-Google-query