Fortnite has had its fair share of bizarre bugs since it launched last September, and the latest is linked to guided missiles, which were reinstated this week after a heavy nerf from Epic. Players have discovered that a missile's turning speed is directly linked to their framerate: the more frames you're getting, the faster the missile will turn.
Other users in the thread have commented that they've experienced similar discrepancies, but they're also pointing out other bugs. For example, if you hold down the W key and the up arrow key at the same time, your missile will travel twice as fast, apparently, which essentially makes it much more useful as a scouting tool.
More interestingly, users are discussing whether there are other features linked directly to your framerate. One user claims that reducing your framerate to a very low number will let you fall faster when you jump out of the battle bus, meaning you reach the ground before anyone else. There's no video proof of that—the user only noticed the difference when they booted up the game on a Macbook Air rather than their regular PC—but others are posting similar stories. I've reached out to Epic to see whether they can confirm the issue.