Lags on Raspberry pi 2

[PepeMax]

Hello everyone, I set up this docker on my raspberry pi, I think it's the PI 2 Model B so with 1GB of RAM.

I have a lot of lags on plex the movies take a long time to load. However, my Raspberry is connected to my router with a cable and I connect to plex from my TV/computer with its local IP address. Is my raspberry the cause ? (I think so)

So I wonder if using a Raspberry Pi 4 would be much more efficient? I'm still hesitating between the 4GB or 8GB of RAM (I'm planning to ask for it as a gift for christmas)

What would you advise me to do?

Thanks