There is no effect when I change between
GPU Acceleration > Intel HD Graphics 4600
GPU Acceleration > GTX 970
or even
GPU Acceleration > No acceleration

GPU load on Intel 4600: 21%
GPU load on GTX 970: 3%

CPU: i7-4790
CPU load for 144hz: 10%
CPU load for 75hz: 23% (Video not slowed)
bonus
CPU load for 60hz: 20% (Video not slowed)

Thank you for your response.

Freshly installed SVP 4.
144hz display.
Windows 10.

I have had this problem both times I've installed SVP 4.  SVP 3.1.7a worked fine for me before I re installed my operating system, but I want to migrate to SVP 4.  As I stated in the title, the video plays slowly (at about 0.55x according to a rough calculation), and the audio plays at normal speed.  Thus far I have not been able to fix the problem.  Has anyone seen this problem or know how to fix it?  If I drag the player to my 60hz monitor, it plays back fine.  It also works great on my 75hz monitor.  The problem only occurs on my main 144hz monitor, which is of course the one I want to watch it on.