Scala performance question

Question

In the article written by Daniel Korzekwa, he said that the performance of following code:

list.map(e => e*2).filter(e => e>10)

is muc

Answer 1

To avoid traversing the list twice, I think the for syntax is a nice option here:

val list2 = for(v <- list1; e = v * 2; if e > 10) yield e