For Array List resizing, why multiply a factor(for size of new array) makes it faster?

Question

For adding element to an array list, the resizing part of the process， why multiplying factor is much faster than just add a constant，the addition would create a very huge amount of memory box in total, hence its slow, but I suppose the multiplication method also creates a huge amount of memory box as well?

https://www.youtube.com/watch?v=pFWS1pGVn9w&list=PL8FaHk7qbOD7M1Zyio0exJXX9zMlG94Gk&index=8

    private void reSizing(int capacity){
        T[] a = (T[]) new Object[capacity];
        System.arraycopy(items,0,a,0,size);
        items = a;
    }


    public void addLast(T x){
        if(size == items.length){
            reSizing(size*2);
        }
        items[size] = x;
        size = size + 1;
    }

the addition version of the code

    private void reSizing(int capacity){
        T[] a = (T[]) new Object[capacity];
        System.arraycopy(items,0,a,0,size);
        items = a;
    }


    public void addLast(T x){
        if(size == items.length){
            reSizing(size + 1);
        }
        items[size] = x;
        size = size + 1;
    }