A portion of the database buffer cache has been restored from the system paging file and is now resident again in memory. ...

%1 (%2) %3A portion of the database buffer cache has been restored from the system paging file and is now resident again in memory. Prior to this, a portion of the database buffer cache had been written out to the system paging file resulting in performance degradation.
Previous cache residency state: %4% (%5 out of %6 buffers) (%7 seconds ago)
Current cache residency state: %8% (%9 out of %10 buffers)