When I wrap the values into value objects (with @Valid), the validation runs very fast (although it supposedly does the same: recurse into values with @Valid and validate with @NotNull and @Min ):

public class Item {

	private Id id;
	private Quantity quantity;

	public @Valid Id getId() { return id; }
	public void setId(Id id) { this.id = id; }
	public @Valid Quantity getQuantity() { return quantity; }
	public void setQuantity(Quantity quantity) { this.quantity = quantity; }

	public static class Id {
	    private Long id;
	    public @NotNull Long getId() { return id; }
	    public void setId(Long id) { this.id = id; }
	}

	public static class Quantity {
	    private int quantity;
	    public @Min(1) int getQuantity() { return quantity; }
	    public void setQuantity(int quantity) { this.quantity = quantity; }
	}
}

0 items, avg. validation time: 49.520402 ms
1 items, avg. validation time: 50.609528 ms
2 items, avg. validation time: 50.88673 ms
5 items, avg. validation time: 50.236684 ms
10 items, avg. validation time: 49.789304 ms
20 items, avg. validation time: 48.713483 ms
50 items, avg. validation time: 50.069192 ms
100 items, avg. validation time: 50.027649 ms
200 items, avg. validation time: 49.037075 ms
500 items, avg. validation time: 50.690123 ms
1000 items, avg. validation time: 50.057061 ms
2500 items, avg. validation time: 49.99966 ms
5000 items, avg. validation time: 48.518808 ms
7500 items, avg. validation time: 50.0492 ms
10000 items, avg. validation time: 50.01165 ms
20000 items, avg. validation time: 48.984054 ms
30000 items, avg. validation time: 51.152249 ms
40000 items, avg. validation time: 50.320894 ms
50000 items, avg. validation time: 50.039272 ms