We use Samba 3.0.22 on a Suse 10 system in connection with OpenLDAP with ca. 25 users. Both SAMBA and OpenLDAP are on the same server.

Performance is usually good when saving files stored on a samba share. But if a file is saved after more then 10 secs without any transmission to samba, a 10 second delay occurs.
Example: Hugo edits a file in Word and uses Ctrl+S to save the file. If there are more then 10 seconds (estimate) between two Ctrl+S, the time for the write operation increases from below a second to more then 10 seconds.

After checking with "File Monitor" from sysinternals I found:
722	16:34:16	WINWORD.EXE:1916	QUERY SECURITY	T:\Joachim\~WRD1690.tmp	SUCCESS		
723	16:34:16	WINWORD.EXE:1916	SET SECURITY	T:\Joachim\~WRD1690.tmp	SUCCESS		
724	16:34:27	WINWORD.EXE:1916	CLOSE	T:\Joachim\~WRD1690.tmp	SUCCESS		
725	16:34:27	WINWORD.EXE:1916	QUERY INFORMATION	T:\Joachim\Netzwerkstruktur.doc	SUCCESS	FileStreamInformation	

A 11 second delay during security changes on the temp file.
I increased the samba log file settings to 10 and checked there:
[2007/02/06 16:31:41, 5] lib/smbldap.c:smbldap_search_ext(1101)
  smbldap_search_ext: base => [dc=master-ldap,dc=gts-systems.de], filter => [(&(sambaSID=S-1-5-21-1623290758-3047616346-2689135926-513)(objectclass=sambaSamAccount))], scope => [2]
[2007/02/06 16:31:41, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:42, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:43, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:44, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:45, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:46, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:47, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:48, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:49, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:50, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:51, 11] lib/smbldap.c:smbldap_open(973)
  smbldap_open: already connected to the LDAP server
[2007/02/06 16:31:52, 10] lib/smbldap.c:smb_ldap_setup_conn(568)
  smb_ldap_setup_connection: ldap://localhost
[2007/02/06 16:31:52, 2] lib/smbldap.c:smbldap_open_connection(724)
  smbldap_open_connection: connection opened
[2007/02/06 16:31:52, 10] lib/smbldap.c:smbldap_connect_system(883)

The LDAP connection seems to be open, but SAMBA does not realize it.
Now I checked the SAMBA sources and found in file "smbldap.c" a function "smbldap_search_ext" which generates the first log entry. Later on this functions enters a while-loop which is left only if the function "another_ldap_try" returns false. This function is:
static int another_ldap_try(struct smbldap_state *ldap_state, int *rc,
			    int *attempts, time_t endtime)
{
	time_t now = time(NULL);
	int open_rc = LDAP_SERVER_DOWN;

	if (*rc != LDAP_SERVER_DOWN)
		goto no_next;

	if (now >= endtime) {
		smbldap_close(ldap_state);
		*rc = LDAP_TIMEOUT;
		goto no_next;
	}

	if (*attempts == 0) {
		got_alarm = False;
		old_handler = CatchSignal(SIGALRM, gotalarm_sig);
		alarm(endtime - now);

		if (ldap_state->pid != sys_getpid())
			smbldap_close(ldap_state);
	}

1>>>>	while (1) {

		if (*attempts != 0)
			smb_msleep(1000);

		*attempts += 1;

		open_rc = smbldap_open(ldap_state);

		if (open_rc == LDAP_SUCCESS) {
			ldap_state->last_use = now;
2>>>>			return True;
		}

		if (open_rc == LDAP_INSUFFICIENT_ACCESS) {
			/* The fact that we are non-root or any other
			 * access-denied condition will not change in the next
			 * round of trying */
			*rc = open_rc;
			break;
		}

		if (got_alarm) {
			*rc = LDAP_TIMEOUT;
			break;
		}

		if (open_rc != LDAP_SUCCESS) {
			DEBUG(1, ("Connection to LDAP server failed for the "
				  "%d try!\n", *attempts));
		}
	}

 no_next:
3>>>>	CatchSignal(SIGALRM, old_handler);
	alarm(0);
	ldap_state->last_use = now;
	return False;
}

Please observe that the forever loop at "1>>>>" is left when a LDAP connection exists 2>>>>! But !!!!! the ciorrect way to leave the loop would be to jump to label "no_next" at 3>>>>.
I think this is a bug. Beyond returning TRUE instead of FALSE also several other ressources are NOT released (signal handler, alarm).

I am not familiar with developing under Linux. So I can not change the source my self and check this. So please comment on my findings.

Thanks for your interest,

J. Hergeth