In The Slums 1, you can go straight from the lockdown cutscene to Seamus' apartment door. Sprint into the far right section of the door, where the doorjamb is. Eventually, the cat will glitch a little and you will be able to see the inside. Move the camera around, and he will go through the wall. Although Seamus isn't here, you can still pick up the broken tracker the same way as normal. Once you do, sprint at the right side of the door this time, closer to the right side of the doorjamb. Basically, try to hit where the door and the wall meet, and the cat will fly right through. Doing this allows you to skip collecting the book and all of the rest of The Slums and Dead End. Get the tracker fixed by Elliot, and immediately after (while you are in his room), reset to the last checkpoint. After the game loads, bring the fixed tracker back to Seamus' apartment by glitching through the door again. He will be waiting and will start the next level. The door, however, is still closed so Seamus won't be allowed to leave, so as soon as the next level starts, quit out of the game and select to redo The Slums 2. This skip saves about 5-7 minutes due to not having to complete The Slums 1 or Dead End.