I thought this was a pretty amusing blog entry (http://www.dailydoseofexcel.com/archives/2007/12/18/google-toolbar-slows-excel/). While I don't think this was intentional, it's a pretty interesting tactic: just install your plug-in to Excel to slow it down. :-)
All in good fun. I haven't used Google desktop search in a while, but I liked it when I had it, so don't read anything into this blog entry.