2) results are sorted by frecency globally, which should increase the quality of the results. for example:
if a highly ranked (by frececnyfrecency) site was visited more than 4 days ago, unlike before, it will appear in the first set of results. so say you visit http://wiki.mozilla.org/WeeklyUpdates once a week for the past year, but it's been 7 days since your last visit. before, because it was more than 4 days old, it would not be in the first chunk of results.
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