Why does my MacBook Pro take so long to go to sleep?

Solution 1:

Considering that PMStats reports a hibernation write time of over eight seconds, this leads me into thinking it is the RAM content.

Exactly. Your RAM contents are written to the disk, in the default sleep mode, called "Safe sleep", which takes longer the more RAM you have. You can modify this with the PMSet command in terminal.

sudo pmset -a hibernatemode 0

and then reboot.

If you disable this option, you can also remove the sleepimage file from /var/vm, and reclaim 8GB of hard disk space. Do note that you will lose data then if you sleep for too long and the battery dies.

Solution 2:

I used to have an episode of slow boot, shutdown, sleep and hibernate. When I turn on verbose mode during boot-up, it was stuck at "Waiting for DSMOS" for a long time. See this link. To solve it, see this link.

Thereafter, all my slow-downs were gone.

Solution 3:

Do you by any chance have a firewire device plugged in? If I try to sleep my Macpro (tower) with an older iSight camera plugged in via Firewire, it takes 10-20 seconds to sleep, vs the normal 2-3.