Question / Help OBS causes extreme frame lag only after 30 or so minutes of streaming.

[Mob]

I am attempting to become a streamer right now. I stream Fortnite content but after around 30 minutes of streaming I start getting extremely bad frame lag on my client. The lag doesn't appear across my computer but occurs only on Fortnite.I can't figure out what the problem is as all my stream settings are pretty standard.