Honestly, the single thing that can improve editing speed is learning how to code with multiple cursors.
It takes about a solid week of practice just to recognise and catch yourself in a situation where using multiple cursors would make you more efficient, and to start using the shortcuts. It takes another week or two to get back up to your old regular speed. After that, you'll find that the old speed ceiling has been removed and you'll continue to get faster and faster until you hit a new ceiling (which is usually your WPM).