You say cabled, so I'm assuming that you've connected the TV to your network via ethernet rather than WiFi?
If you're using ethernet, I suggest you try WiFi. My TV is much more responsive since only connecting via WiFi.
I've been asking myself how this can be. And the only answer I've come up with is that WebOS wouldn't originally have had an ethernet driver as it was intended to run on mobile devices. So I'm guessing that LG added an ethernet driver and they've botched it.
Either way, I'm sending my TV back and buying an alternative brand. It's still pretty terrible (but less so since I'm on Wifi).