Fortnite Performance mode issues

There is a weird translucent grid carbon fiber like looking overlay where shadows would once be when using performance mode. Please fix this, it also causes frame drops.

Below are two more sources from players with the same problem:

https://www.reddit.com/r/FortNiteBR/comments/1paz0uk/performance_mode_carbon_fiber_shadows_bug/

https://www.reddit.com/r/FortNiteBR/comments/1ood2cc/visual_noise_and_distortion_bug_performance_mode/