Comment 44 for bug 1464917

I am no expert but I looked into the systemd shutdown.target as well and found no parameters that can be changed. I also performed a swap test where I loaded the swap partition to over 54% roughly 4.2 gig while my ram was at 87% full. I have 3.7 gig ram available and 8.1 gig swap on my machine. I loaded the system using Gimp opening and entire folder of photos, opening a browser and streaming a youtube movie. I then closed all applications and waited for 20 minutes with the monitor open. The swap file did lose half of its stored data to about 2 gig but then it seemed to pause at that point for a long time, longer than I was willing to wait. I then ran:
sudo swapoff -a && systemctl poweroff

The swapoff process took another 10+ minutes and then the shutdown took place without the hang.

It is my belief that the swap management app/function built into the OS is the issue or at least part of it.