Took my exam approximately 2 years ago.
For me the nav exam was the only one where I needed the full amount of time allocated. However, I used a disproportionate amount of time findng the start, finish and divert airfields from the latitude and longitude coordinates. The result of this was that I was under time pressure for the rest of the exam.
As 24Carott has said, finding locations is easy, and it is if you have practised it. Unfortunately I hadn't (although I was confident about most of the subject I had overlooked the basics in chapter 1) and since this is just about the first thing you need to do in the exam it is a nerve settler to get off to a smooth start by doing this fluently.
Also (and another very basic sounding thing) is try to organise your chart, pens, ruler etc. before the clock starts ticking. My chart was tighty rolled and needed objects at the four corners to keep it on the table. Take some bluetak in with you and you will look like a pro!
Since qualifying for my PPL I find that a big thing about flying is that it is important to get prosaic matters like this sorted, as boring as it may sound.
Good luck