Something's broken in JNDI ?

Consider the following unit test :

package ldapcrap;

import java.util.Hashtable;

import javax.naming.NamingException;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

import junit.framework.TestCase;

@SuppressWarnings("unchecked")
public class CrapTest extends TestCase {

 private Hashtable env;

 @Override
 protected void setUp() throws Exception {
  super.setUp();

  env = new Hashtable();

  env.put("java.naming.factory.initial",
    "com.sun.jndi.ldap.LdapCtxFactory");
  env.put("java.naming.provider.url", "ldap://10.0.0.5");
  env.put(DirContext.SECURITY_AUTHENTICATION, "simple");
 }

 public void testJNDIisCrap() throws NamingException {
  DirContext ctx = null;
  try {
   ctx = new InitialDirContext(env);
  } catch (Throwable t) {
   fail("test failed");
  } finally {
   ctx.close();
  }
 }

 public void testInALoop() throws NamingException {
  long time;
  int COUNT;
   
  COUNT = 1000;
  time = System.currentTimeMillis();
  for (int i = 0; i < COUNT; i++) {
   testJNDIisCrap();
  }
  time = System.currentTimeMillis() - time;
  System.out.println("did "+COUNT+" in "+(time/1000)+"second(s).");

  COUNT = 10000;
  time = System.currentTimeMillis();
  for (int i = 0; i < COUNT; i++) {
   testJNDIisCrap();
  }
  time = System.currentTimeMillis() - time;
  System.out.println("did "+COUNT+" in "+(time/1000)+"second(s).");

  COUNT = 100000;
  time = System.currentTimeMillis();
  for (int i = 0; i < COUNT; i++) {
   testJNDIisCrap();
  }
  time = System.currentTimeMillis() - time;
  System.out.println("did "+COUNT+" in "+(time/1000)+"second(s).");
}

 @Override
 protected void tearDown() throws Exception {
  super.tearDown();
 }
}

Here's what it shows when openldap is running on 32bit debian etch:
did 1000 in 2second(s).
did 10000 in 28second(s).
did 100000 in 441second(s).

Something sounds wrong with those results as the unit test is linear : open/close, open/close. As long as we do not get 2, 20, 200 or something approaching, either my test code is wrong, or some server configuration is wrong.

The results on 64bit lenny are:
did 1000 in 2second(s).
did 10000 in 19second(s).

No third result, it broke and the test failed with some useless null pointer. Let's "strace -f" the slapd process on lenny :
did 1000 in 13second(s).
did 10000 in 382second(s).

Ok, will take too long and seems stalled. Will write strace output to a file "strace -f -o slapd.log".

Starts good :
did 1000 in 6second(s).
did 10000 in 61second(s).

But then...
did 100000 in 1049second(s).

I expected between 500 & 620 seconds (I hoped the jvm JIT will do its job). I used my computer in the meantime, but not that much.

Still analysing the strace output, but if someone knows what is wrong in my test...