Which is better coding style?

Is better to code
1. In a way can be readable easily on first sight but maybe inefficient
or
2. That is very efficient and short but more complicated to read and understand

My instructor (a very scary prof) always tells us to go to option #1. Yes you can still do option #2 if you provider enough comments to explain.

But if you do option #1, you will not need to comment alot about your code because your code will speak for itself because of its easy readability.

What do you think?

Stick with #1, unless it's a piece of code you need as optimized as theoretically possible (written in assembler, of course).

When you are working on a proc/func that does something complicated and unique (to optimize performance), use #2, but comment the algorithm and provide the same proc/func in the format of #1.