ABCL, For implementing MOP-like objects these times are something to consider. What I draw from it is when not messing with arrays (array bounds checking). Every case is better than. JVM-L, Do these tests with times make sense? package ArrayTests; public class ArrayVsClass { public static void main(String[] args) { long lVectorStartTime = System.currentTimeMillis(); int iterations = Integer.MAX_VALUE; while (iterations-- > 0) { // int iterations2 = 10; //while (iterations2-- > 0) { //testArray(); // ARRAY // vs //testGETFIELD(); // GETFIELD // vs testIBean(); // INVOKE INTERFACE // vs //testBean(); // INVOKE VIRTUAL // vs //testABean(); // INVOKE VIRTUAL POSSIBLY THROW // vs //testSlots(); // INVOKE FOR AVALUE } } long lVectorRunTime = System.currentTimeMillis() - lVectorStartTime; System.out.println("Bench time: " + lVectorRunTime); } // SLOTS time: 33157,33250,33156 public static void testSlots() { ClassWithSlots oneSlot = new ClassWithSlots(6); int iterations = Integer.MAX_VALUE; long result = 0; while (iterations-- > 0) { result += oneSlot.getValue(); } } // Array time: 18438,18437,18422 public static void testArray() { final long[] accessArray = new long[] { 6 }; int iterations = Integer.MAX_VALUE; long result = 0; while (iterations-- > 0) { result += accessArray[0]; } } // GETFIELD time: 14688,14531,14453 public static void testGETFIELD() { ClassWithOneSlot oneSlot = new ClassWithOneSlot(6); int iterations = Integer.MAX_VALUE; long result = 0; while (iterations-- > 0) { result += oneSlot.slot; } } // INVOKE VIRTUAL time: 14750,14594,14719 public static void testBean() { ClassWithOneSlot oneSlot = new ClassWithOneSlot(6); int iterations = Integer.MAX_VALUE; long result = 0; while (iterations-- > 0) { result += oneSlot.getValue(); } } // INVOKE INTERFACE time: 14469,14610,14859 public static void testIBean() { IBeanWithOneSlot oneSlot = new ClassWithOneSlot(6); int iterations = Integer.MAX_VALUE; long result = 0; while (iterations-- > 0) { result += oneSlot.getValue(); } } // INVOKE VIRTUAL POSSIBLY THROW time: 14641,14594,14547 public static void testABean() { AClassWithOneSlot oneSlot = new ClassWithOneSlot(6); int iterations = Integer.MAX_VALUE; long result = 0; while (iterations-- > 0) { result += oneSlot.getValue(); } } static interface IBeanWithOneSlot { public long getValue(); } static class ClassWithOneSlot extends AClassWithOneSlot implements IBeanWithOneSlot { final public long slot; ClassWithOneSlot(long s) { slot = s; } @Override final public long getValue() { return slot; } } static class ClassWithSlots { final public long[] slots = new long[1]; ClassWithSlots(long s) { slots[0] = s; } final public long getValue() { return slots[0]; } } static abstract class AClassWithOneSlot implements IBeanWithOneSlot { @Override public long getValue() { throw new NullPointerException(); } } }