What can I do to maximize the performance of my openldap setup which running in master-slave mode using syncrepl? 
System has 8GM RAM and 4GB swap space
Openldap-2.3.32 and DB.4.5
Total dn count is 2450000.
LDIF size is 670MB using ldapsearch
dbd size is :
du -c -h *.bdb
69M     authenticationId.bdb
227M    cn.bdb
602M    dn2id.bdb
27M     entryCSN.bdb
24M     entryUUID.bdb
2.5G    id2entry.bdb
6.4M    mail.bdb
4.6M    objectClass.bdb
16M     ou.bdb
263M    sn.bdb
740M    uid.bdb
4.4G    total
Portion of slapd.conf:
cachesize 50000
checkpoint 4096 10
sizelimit 2500000
# Set the database in memory cache size.
set_cachesize    2 0 1
# Set database flags.
set_flags DB_TXN_NOSYNC
set_lk_max_locks 2000
set_lk_max_objects 1000
set_lk_max_lockers 1000
set_txn_timeout         3000000
set_lock_timeout        3000000
set_lg_regionmax        1048576
set_lg_max              10485760
set_lg_bsize            2097152
set_lg_dir               /usr/local/var/master/logs

db_stat -h /usr/local/master/db -m | head -n 2
2GB     Total cache size
1       Number of caches

Pawan Kumar