it's in the documentation as well. for delete:
> Deletes the item at index i by moving all x[i+1..] items by one position. > > > This is an O(n) operation. for del > Deletes the item at index i by moving all x[i+1..] items by one position. > > > This is an O(n) operation. so del is faster, but if you care about the order of the seq you can't use it.
