Sketch had brought totally new standards for file sizes. You no longer see 10 GB Photoshop files all over the place. Nevertheless, huge Sketch files exist, and they slow down Sketch. As a result, your productivity slows down as well. Let’s be honest: It's not the design files that become bigger by magic. It’s designers who fill their files with unused, unoptimized and hidden elements that take unnecessary space. We have faced this problem in our startup, Flawless App.Original Source