You’ll find the option for Performance Mode in Fortnite’s settings menu starting from 15th December. It lowers some visual quality settings, and therefore improve the performance of the CPU and GPU … giving you better framerates.
Taken from Engadget … With its modest minimum system requirements, you can play Fortnite on almost any computer made in the last decade, but the experience may not be the best. Fortunately, Epic Games is introducing a new Performance Mode to help out those who are stuck with less capable systems.
Starting on December 15th (tomorrow), you’ll find Performance Mode in Fortnite’s settings menu. In a blog post spotted by Polygon, Epic says it allows the battle-royale to “run better than ever before and maintain a smoother framerate.” It does so by lowering some visual quality settings, thereby lightening the workload on your computer’s CPU and GPU. If you’re playing Fortnite on a system that just barely meets the game’s minimum system requirements, it will prompt you to try out the feature the next time you jump into the title. You can turn off Performance Mode at any point afterwards.
… A new option available through the Epic Games Launcher will allow to opt out of downloading the game’s high-resolution textures. On most systems, that should save you about 14GB of internal storage — that’s on top of the space you’re already saving after Epic recently streamlined the PC install of Fortnite to make it take up less space. If you don’t need the high-resolution textures, you can get Fortnite down to about 17GB with the tweak.