There are slight differences in speeds between the different possible ways to write the above (off the top of my head, I can think of at least 3 other ways). However, as big.nerd suggests, this difference in speed could probably only be measured by using each method several thousand (or more?) times - and even then, it's not going to be a huge difference.
In other words, the negligible amount of CPU time you'd save is nowhere near enough of a benefit to spend the time figuring out which method is the most efficient. That pretty much leaves it as a matter of preference; which one is easier for you as a programmer to read and analyze?
