Garrysmod server takes 80% cpu. dedicated.

VPS details :
400 GB Disk storage
4 GB RAM
4×3.4 Ghz CPU Cores
500 Mbit/s(guaranteed) – 1 Gbit/s 8 TB Traffic
Linux Based(centos 6.4 64bits)

And garrysmod server just have tone of lags.
I tried to set this server commands at the server cfg

// Optimizations

Quote:fps_max 600
sv_maxupdaterate 101
sv_minupdaterate 50
sv_maxcmdrate 101
sv_mincmdrate 50
sv_client_min_interp_ratio 0
sv_maxrate 30000
sv_minrate 25000

run command :
screen -A -m -d -S c45 ./srcds_run -console -game garrysmod +maxplayers 40 +exec c45.cfg +map rp_city45_2013.bsp -secure -port 26543 +gamemode combinecontrol

I have the same problem, 80-100$ cpu uses.
Any help ??