"I'm guessing" Yes, you are. I'm saying this is a more interesting question, and one that isn't answered. Because the reality is that if you're appending just

"I'm guessing" Yes, you are. I'm saying this is a more interesting question, and one that isn't answered. Because the reality is that if you're appending just a handful of things together, the idiomatic approach is to concatenate them, and this optimization comes into play. If you're concatenating a lot of items together...you probably already have a list, and the idiomatic approach to join them is probably faster than a for loop to concat them over and over. So the question then, is is there a point where idiomatically it makes more sense to join things (putting them in a list if they aren't already, but they might be; depends on the example), but this will be more efficient?