First thing, compare the network speed and statistics on your console as well as on speedtest using a laptop or mobile device. On your Xbox: Settings > General > Network Settings > Test Network Speed and Statistics. If it's the same and indeed high ping on both, the issue can be with your network connection.

The experience of playing Call of Duty: Modern Warfare 2 Remastered through a Radeon RX 580 8GB is going to deliver a solid 80 FPS. Note that those results would be running at High and 1920x1080 screen res.

This time, the game does ask for some pretty hefty specs even in its minimum. We're finally up to at least 8 GB of RAM to be able to run the title.