Multitasking is a myth. Your brain cannot truly focus on multiple things at once. It switches between them rapidly, and each switch costs time and mental energy. You work slower and make more mistakes.
Instead, work on one task at a time. Close everything else. If you are writing, close email and other tabs. If you are designing, close everything except your design tool. Give your full attention to one thing.
This single focus increases both speed and quality. You work faster because you are not switching contexts. You work better because your full attention is on the task. The work becomes more enjoyable because you can enter a state of flow.
Try it with your next task. Close everything else. Work on just that one thing until it is done. Notice how much faster and better you work when you give something your full attention.