lag issue when using tv as 2nd monitor via HDMI

[stevesound]

Hi there,
this isn't directly related to Protools I know, but since some people on here work in music for tv/commercials (as I do) I thought I might find a suggestion or two!

I have a Mac Pro (Late 2013) with an apple monitor which is all working fine, but decided to get a tv so that scoring to picture would be more widescreen. I have a Sharp tv (40UG7252K) hooked up via HDMI and it's all connected fine. The problem is that there is a lag of about 24frames+ on playback, which makes it impossible to use when working on tightly edited material.

I noticed that the HDMI signal in to the tv is only 30Hz (the tv picture quality of the tv is 50Hz). Could this be the basic issue? Do I need to get a higher hz value on the tv? Or can I get something like an AJA T-Tap to improve the sync?

Any advice would be a massive help!

thanks!!
Steve