> if you assign to an index that's way past the end of your the elements array, V8 may downgrade the elements to dictionary mode... avoid copying from the back

> if you assign to an index that's way past the end of your the elements array, V8 may downgrade the elements to dictionary mode... avoid copying from the back Sublime I think still has the snippet for "optimized for loop" that runs in reverse. I have never seen that improve performance, and I didn't know that it could actually be harmful if used to initialize an array.