Tom's Hardware as published a GPU Performance Hierarchy list that ranks all the current video cards from fastest to slowest.
When you want to run games or do high-end creative work like 4K video editing, your graphics card plays the biggest role in determining performance. Get a good GPU, and you can play recent games at smooth frame rates; get one of the best GPUs for gaming and you can enjoy those games at high resolution, with the special effects turned all the way up.
