Despite the somewhat click-bate-ish title, the use of fairly simple tools (yes, as simple as keyboard shortcuts) may just be the steppingstone when it comes to kicking of performance improvements of your system, starting from the code base.
To satisfy your hunger – the meager ctrl+x/ctrl+v* might just inherit the earth when it comes to code cleanliness and maintainability – which have direct impact on performance and scalability. Moving code to a different file may seem like a very small feat, but it may not only save you from scrolling over that specific piece of code over and over for the rest of your career looking for something else, but will allow you to better decouple your code now, and resist the temptation to increase coupling withing your existing code.
Try it now, find the biggest, longest code file you have, and split it, and tell me how It all worked out.
*ctrl+k/ctrl+y, ctrl+w/ctrl+y, command+x/command+v etc. (you get the point)