My sons are playing shit-tons of Fortnite these days, on what I believe to be reasonably fast computers. Still, they keep complaining about lag (when you die, it’s always because lag). The monitors are old ones that I picked up at Salvation Army about 5 years ago. Would upgrading the monitors have any affect on the lag complaints, or is it purely a CPU/video card issue?

Here are what I believe to be the pertinent facts about their computers: