External 4k Monitor via HDMI video playback lagging as well as audio delay

Hello All,

I have been experiencing a video playback lagging as well as audio delay when using my external monitor for my work space. My computer monitor is project and clip space. 

My Mac is an

iMac Pro 2017

1. 2.3 Ghz Intel Xeon W

Graphics Radeon pro Vegas 64

External monitor is a 58”Samsung 4K

I’m using a USB-C dongle to HDMI out of the iMac to get into the Samsung.

If I keep the work space on the iMac all is good but my preference is to use the Samsung for my work space.

Any solutions?