How are you connecting to your new TV? HDMI?
The version of the HDMI port on your TV could limit you to 30 fps if you are running at 4K.
Some TVs have different quality/versions of HDMI ports. Port 1 is usually the higher quality port that is optimized for PCs or other high performance applications.
Hopefully, this is a minor setting problem. But if you set your display to 1080p and you can get 60 fps, then it is probably the HDMI port on the TV that is limiting you to 30 fps.