Completing a PhD sooner: what does it take?
The first thing you need to ask yourself is: do you really want a PhD? At its core a PhD is nothing more and nothing less than "vocational education for researchers". In a PhD program you will learn about and get some experience in doing real research. If you don't want to become a researcher, then what is the value to you? There is the status that some feel comes attached with the title, but is that really worth a couple of years of your life? 

Assuming you really want to go through with this, then you need to realize that it will take at least 3 years and probably more. That is a long time, so you need to approach that more like a marathon than as a sprint. So don't go in and start burning the midnight oil, because you will only burn out yourself before you are done with your PhD. This is a very common mistake among PhD students. 

The only PhD student I know who made it in about 3 years had a completely different approach. She had a plan that was realistic, and she stuck to it. Making a realistic plan for your thesis is very hard. She managged because she already had experience doing research and was already well versed in her topic. She was also extremely disciplined in how she managed her time, and this ment that while at work she worked very hard, but she would not work in the evenings and not work in the weekends. She was able to work that hard and that focussed for 3 years on end because she did not work in the evenings and in the weekends. 

I am not that person. I whish I was that disciplined, but I am not, and it took me 7 years to finish my PhD...