If your Mac is sluggish, you frequently see the dreaded beachball and get warning dialogs about low disk space:

"The core issue seems to be that the virtual memory manager is bad at managing which pages should be freed from the inactive state and which ones should be paged out to disk (and, consequently, back from disk)."

http://workstuff.tumblr.com/post/20464780085/something-is-de...