Ruby Array concat versus + speed?

Question

I did small performance test of Ruby\'s array concat() vs + operation and concat() was way too fast.

I however am not clear on why

Answer 1

According to the Ruby docs, the difference is:

Array#+ :

Concatenation — Returns a new array built by concatenating the two arrays together to produce a third array.

Array#concat :

Array#concat : Appends the elements of other_ary to self.

So the + operator will create a new array each time it is called (which is expensive), while concat only appends the new element.