You guessed it. Too much overhead. Once HTTPs took over, I had to find other options as implementating HTTPS and SSL on the Pronto was performance-prohibitive.

My recommendation is to implement this in Node.js (or Python if you must) where all the libraries you would likely need are available. Host this as a service on a Raspberry Pi.

As part of your software, implement a front end (either HTTP, WebSockets, or raw socket) that accepts commands from the Pronto and sends them to the LG.

I am currently running multiple things this way. In fact, my OpenWeatherMap (HTTP REST -> HTTPS REST) proxy runs beautifully as does my Denon/Marantz(TCP->TCP) and Bryston DAC (TCP->HTTP) proxies.

I could have done the Denon/Marantz on the Pronto but I wanted to be able to use 'Macro' commands such as _MVSS which, behind the scenes issues:

MV?
MU?
MS?
SI?

to my Marantz Preamp. The pronto sends 1 request and then simply processes 4 events.