public inline class Vector {

    private final double x;
    private final double y;

    public Vector(double x, double y) {
        this.x = x;
        this.y = y;
    }

    public Vector add(Vector v) {
        return new Vector(x + v.x, y + v.y);
    }

    @Override
    public String toString() {
        return "{" + x + "," + y + "}";
    }

}

TEST:

Instant start = Instant.now();
Vector v = new Vector(0, 0);
for (long i = 0; i < 5000000000L; i++) {
    v = v.add(v);
}

Instant end = Instant.now();
Duration d = Duration.between(start,end);
System.out.println(d + v.toString());