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

A 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: %1% (%2 out of %3 buffers) (%4 seconds ago)
Current cache residency state: %5% (%6 out of %7 buffers)