How to Screen Mirror Without All the Lag?

So I'm trying to transition from watching stuff on my phone to watching stuff on this TV that I was given but never really used. Last night, I tried using Smart View on my android to watch a show (I use a website to watch all my stuff rather than paying multiple streaming services). I was also on a discord call so I only shared my Firefox window so the call didn't also go through the TV, and there was about 2 or 3 seconds of lag. It's annoying and I've been trying to do some research to solve this before my friend and I hang out again. So far, all I've learned that one of the best 3 apps (according so some post) is apple only, and the other 2 apps I can't even find. Also I learned that I can't Chromecast since I'm using Firefox, so I'm not really sure what to do, besides getting a long ass HDMI, Bluetooth keyboard and mouse, and just use my PC to watch stuff instead, or just stick with my phone. If anyone has a solution, I'd love to hear it and test it for myself, thanks