Definitely try raising sysctl vfs.vm_cycle_point as Sam suggested. This
can be done on a live system. I would like to try to avoid ripping
up the buffer cache this close to release.
Try setting it to 40 (it defaults to 23). The max value is 64
which will effectively put all non-memory-mapped file data on the
inactive queue, including any data which is repeatedly accessed.
-Matt