Is it bad to have Stockfish show multiple lines?

For some reason I got the impression that it is more efficient to have an analysis engine like Stockfish 7 only show one line of analysis, as opposed to two or three. In other words, if you want to find out the best move in the position in the least possible amount of time, it is best to only have Stockfish show one line instead of 2 because if you show 2, it will have to spend extra resources calculating out the 2nd line and thus waste time. Is this notion correct, or am I wrong? I'm hoping that I am wrong, because I like seeing the second best option, and when I only have stockfish calculate one line in Chessbase, the length of the line/variation is constantly changing, and sometimes I can only view the first move of the variation that Stockfish is currently analyzing. 

Thank you for your help!

I like looking at 4 lines in post game analysis. If you have a multi-core fairly modern machine, I don't think the performance hit will be too noticeable. 

Thank you very much for your answer!

It's actually preferable to use multiPV of 2-3 when analysing your games.  The time to depth will be slower, but you'll find it more accurate.