Odd problem with open-ldap

[Matt <mhoppes@gmail.com>]

Hi,
I'm running open-ldap and it's very nice.   Having one strange anomoly
I'm hoping someone can help me with.

Doing lookups is very fast, and even putting data in or erasing data is fast.  
I have about 40,000 entries in the database.
If I add or remove up to 2,000 at a time (ie select 2,000 entries and
hit delete) they go very fast , however if I select all 40,000
entries, and hit delete, there seems to be a delay of about 5 - 7
seconds between every transacation.  (meanwhile if I go to another
browser and browse/add/edit/delete entries they are fast.. so it's not
like the database is overloaded).  A debug shows nothing weird, just
that the transactions are having a delay of up to 7 seconds.
I've even tried this with only 15,000 entries in the database, and it
still takes about 7 seconds per transaction.. yet if I do them in
small bunches of like 2,000 it works fine.

It almost seems like the more I select the longer it takes.. for
instance if I select 7,000 entries, the delay is about 1 1/2 to 2
seconds.
And 5,000 entries has a delay of about 1/2 a second.
Meanwhile doing 700 entries has no delay and the records actively fly
past my screen as I watch them vanish on the slapd -d 9 debug console.

I have the following in my config:
directory       /usr/local/var/openldap-ldbm
# Indices to maintain
index   objectClass,x500uniqueIdentifier,uid,mail,mailAlternateAddress  eq

my ldap.conf is running on the defaults:
SIZELIMIT      12
TIMELIMIT      15
DEREF          never

in my database directory I have:

-rw-------    1 root     root      8589312 Dec 30 09:08 dn2id.dbb
-rw-------    1 root     root     29884416 Dec 30 09:08 id2entry.dbb
-rw-------    1 root     root         8192 Dec 30 08:18 mailAlternateAddress.dbb
-rw-------    1 root     root      1548288 Dec 30 09:08 mail.dbb
-rw-------    1 root     root         8192 Dec 30 08:41 nextid.dbb
-rw-------    1 root     root       253952 Dec 30 08:54 objectClass.dbb
-rw-------    1 root     root      1564672 Dec 30 09:08 uid.dbb
-rw-------    1 root     root      1679360 Dec 30 09:08 x500UniqueIdentifier.dbb


What's up with that, or what other information is needed?