I put together a quick experiment to compare the relative performance of three approaches to providing toString():  generated by Eclipse, Apache Reflection, and XML Marshalling.  All three approaches support inheritance.

Summary:

Eclipse generated toString() total elapsed time 141 ms.  Average: 7 usec.

Apache based reflection total elapsed time 1481 ms.  Average: 74 usec.

XML marshalling total elapsed time 828 ms.  Average: 41 usec.

<code>

package tutorial;

import java.io.ByteArrayOutputStream;
import java.util.Arrays;
import java.util.Date;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.namespace.QName;

import org.apache.commons.lang3.builder.ReflectionToStringBuilder;

/**
 * Compare relative performance results of various approaches to implementing toString()
 *
 * @author greg totsline
 *
 */
public class ToStringPerformance extends ToStringParent {
 
 private int x = 1;
 private float y = 4.4f;
 private long z = 123456;
 private Date date = new Date();
 private String stringData = "some string data";
 private String[] stringArray = {"one", "two", "three"};
 
 private JAXBContext context;
 
 public ToStringPerformance()
 {
 try {
 context = JAXBContext.newInstance(ToStringPerformance.class);
 } catch (JAXBException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 }

 /**
  * @param args number of runs to perform
  */
 public static void main(String[] args) {
 
 int numRuns = 0;
 
 if (args.length == 0)
 {
 numRuns = 10000;  // default
 }
 else
 {
 numRuns = Integer.parseInt(args[0]);
 }
 System.out.println("Executing " + numRuns + " runs");
 
 ToStringPerformance perfTester = new ToStringPerformance();
 
 /**
  *  load class dependencies by doing an initial call so overhead is not included in measured execution times that follow
  */
 testApacheRelection(perfTester);
 perfTester.toString();
 perfTester.testMarshallToXML(perfTester, ToStringPerformance.class);
 System.nanoTime();
 
 long startTime = System.nanoTime();
 for(int i = 0; i < numRuns; i++)
 { 
  perfTester.toString();   
 }
 long estimatedTime = System.nanoTime() - startTime;
 System.out.println("Eclipse generated toString() total elapsed time " + estimatedTime / 1000000 + " ms.  Average: " + (estimatedTime / 1000) / numRuns + " usec.");
 
 startTime = System.nanoTime();
 for(int i = 0; i < numRuns; i++)
 { 
  testApacheRelection(perfTester);   
 }
 estimatedTime = System.nanoTime() - startTime;
 System.out.println("Apache based reflection total elapsed time " + estimatedTime / 1000000 + " ms.  Average: " + (estimatedTime / 1000) / numRuns + " usec.");
 
 startTime = System.nanoTime();
 for(int i = 0; i < numRuns; i++)
 {
 perfTester.testMarshallToXML(perfTester, ToStringPerformance.class);
 }
 estimatedTime = System.nanoTime() - startTime;
 System.out.println("XML marshalling total elapsed time " + estimatedTime / 1000000 + " ms.  Average: " + (estimatedTime / 1000) / numRuns + " usec.");
 
 
 }
 
 /**
  * Apache based reflection approach to toString()
  * @param perfTester
  * @return
  */
 private static String testApacheRelection(ToStringPerformance perfTester) {
 String result = ReflectionToStringBuilder.toString(perfTester);
 return result;
 
 }

 /**
  * Eclpise generated
  * @see tutorial.ToStringParent#toString()
  */
 @Override
 public String toString() {
 String baseClass = super.toString();
 return baseClass + " ToStringPerformance [x=" + x + ", y=" + y + ", z=" + z
 + ", date=" + date + ", stringData=" + stringData
 + ", stringArray=" + Arrays.toString(stringArray) + "]";
 }

 /**
  * XML marshalled approach to toString()
  * @param objectToBeMarshalled
  * @param clazz
  * @return
  */
 public <T> String testMarshallToXML(T objectToBeMarshalled, Class<T> clazz)
 {
 ByteArrayOutputStream baos = new ByteArrayOutputStream(512);
 String outputString = null;
  try
  {
  Marshaller marshaller = context.createMarshaller();
  marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
 
  marshaller.marshal(new JAXBElement<T>(new QName("", clazz.getSimpleName()),
   clazz, objectToBeMarshalled), baos);
 
  outputString = baos.toString();
 
  }
  catch (JAXBException e) {
  e.printStackTrace();
  }
  return outputString;
 }
 

 public int getX() {
 return x;
 }

 public void setX(int x) {
 this.x = x;
 }

 public float getY() {
 return y;
 }

 public void setY(float y) {
 this.y = y;
 }

 public long getZ() {
 return z;
 }

 public void setZ(long z) {
 this.z = z;
 }

 public Date getDate() {
 return date;
 }

 public void setDate(Date date) {
 this.date = date;
 }

 public String getStringData() {
 return stringData;
 }

 public void setStringData(String stringData) {
 this.stringData = stringData;
 }

 public String[] getStringArray() {
 return stringArray;
 }

 public void setStringArray(String[] stringArray) {
 this.stringArray = stringArray;
 }

</code>

package tutorial;

import java.math.BigDecimal;

public class ToStringParent
{
 int j = 1;
 float k = 3.14f;
 double l = 1.234567;
 BigDecimal bigD = new BigDecimal("5551212.1234");
 public int getJ() {
 return j;
 }
 public void setJ(int j) {
 this.j = j;
 }
 public float getK() {
 return k;
 }
 public void setK(float k) {
 this.k = k;
 }
 public double getL() {
 return l;
 }
 public void setL(double l) {
 this.l = l;
 }
 public BigDecimal getBigD() {
 return bigD;
 }
 public void setBigD(BigDecimal bigD) {
 this.bigD = bigD;
 }
 
 @Override
 public String toString() {
 return "ToStringParent [j=" + j + ", k=" + k + ", l=" + l + ", bigD="
 + bigD + "]";
 }
 
 
}

 
}