Problemas con Samba SMB lentitud

Buenas tardes, les comento mi problema...

Tengo una red de 20 computadoras con un servidor centos de 64bits el cual cuenta con samba para compartir carpetas, todo va de maravilla, puedo compartir carpetas e impresoras sin ningún problema.

El problema es:

En ocasiones la navegación entre las carpetas es muy fluida y en otras ocasiones es demasiado lenta (al rededor de 25 segundos) en cambiar de carpetas, esto es independiente a cuantos usuarios haya conectados, alguna idea de lo que sea??

les dejo mi smb.conf

[global]
# ----------------------- Network Related Options -------------------------
workgroup = WORKGROUP
server string = Samba Version %v
;netbios name = MYSERVER
;interfaces = lo eth0 192.168.12.2/24 192.168.13.2/24
interfaces = lo eth0 192.168.45.250/24
;hosts allow = 127. 192.168.12. 192.168.13.
hosts allow = 127. 10.0.2. 192.168.45. 192.168.40. 192.168.41. 192.168.43.
# --------------------------- Logging Options -----------------------------
#
# Log File let you specify where to put logs and how to split them up.
#
# Max Log Size let you specify the max size log files should reach
# logs split per machine
log file = /var/log/samba/log.%m
# max 50KB per log file, then rotate
max log size = 50
# ----------------------- Standalone Server Options ------------------------
#
# Scurity can be set to user, share(deprecated) or server(deprecated)
#
# Backend to store user information in. New installations should
security = user
passdb backend = tdbsam
# ----------------------- Domain Members Options ------------------------
;security = domain
;passdb backend = tdbsam
;realm = MY_REALM
;password server = <NT-Server-Name>
# ----------------------- Domain Controller Options ------------------------
#
#
;security = user
;passdb backend = tdbsam
;domain master = yes
;domain logons = yes
# the login script name depends on the machine name
;logon script = %m.bat
# the login script name depends on the unix user used
;logon script = %u.bat
;logon path = \\%L\Profiles\%u
# disables profiles support by specifing an empty path
;logon path =
;add user script = /usr/sbin/useradd "%u" -n -g users
;add group script = /usr/sbin/groupadd "%g"
;add machine script = /usr/sbin/useradd -n -c "Workstation (%u)" -M -d /nohome -s /bin/false "%u"
;delete user script = /usr/sbin/userdel "%u"
;delete user from group script = /usr/sbin/userdel "%u" "%g"
;delete group script = /usr/sbin/groupdel "%g"
# ----------------------- Browser Control Options ----------------------------
;local master = no
;os level = 33
;preferred master = yes
#----------------------------- Name Resolution -------------------------------
;wins support = yes
;wins server = w.x.y.z
;wins proxy = yes
;dns proxy = yes

--------------------------- Filesystem Options ---------------------------
be set just per share, setting them in global
# makes them the default for all shares
;map archive = no
;map hidden = no
;map read only = no
;map system = no
;store dos attributes = yes