Before you search deeply for marginal gains in performance it is important that you have taken care of what precedes marginal gains. Sometimes it is so obvious it is easy to overlook. It is really quite simple, it is a process that is necessary to achieve at the highest level:
Know the Basics
Master and Refine the Basics
Don’t Deviate From the Basics
Once this process is clear then and only then will marginal gains be of significance in performance. It's all pretty basic!