server props lagging (garrysmod)

[celestiasslave]

My fps is good on the server nothing is lagging untill i spawn 1 or more entities this cause massive prop lag i dont know why i have checked my cpu usage my ram usage
but nothing seem to be the problem please help me...

specs: 8 gb ram, Anthlon x4 750k,windows 8.1 pro

servercfg:
[/font]
logging on
hostname "celestiasslave's server"
rcon_password ""
sv_password ""
sv_region 255
sv_lan 0
sv_logbans 1
sv_logecho 1
sv_logfile 1
sv_log_onefile 0
sv_noclipspeed 5
sv_noclipaccelerate 5
//Sandbox Settings
sbox_weapons 0
sbox_allownpcs 1
sbox_godmode 0
sbox_plpldamage 0
sbox_playergod 0
sbox_noclip 0
sbox_maxprops 150
sbox_maxragdolls 5
sbox_maxnpcs 10
sbox_maxballoons 10
sbox_maxeffects 50
sbox_maxdynamite 10
sbox_maxlamps 20
sbox_maxthrusters 30
sbox_maxwheels 20
sbox_maxhoverballs 20
sbox_maxvehicles 6
sbox_maxbuttons 20
sbox_maxsents 20
sbox_maxemitters 5
sbox_maxspawners 3
sbox_maxturrets 2
//Server Settings
net_maxfilesize 30
sv_minrate 0
sv_maxrate 2500
decalfrequency 10
sv_maxupdaterate 66
sv_minupdaterate 10
//Execute ban files
exec banned_ip.cfg
exec banned_user.cfg