BE AWARE!! that overclocking can DESTROY the Raspberry device. It’s your own fault if something goes wrong!!
Create folder: mkdir /media/boot
Mounting the Boot partition: mount /dev/mmcblk0p1 /media/boot
And then run: vi /media/boot/config.txt
Add in the bottom of the file:
Save and quit.
Last time run: reboot
Now your Raspberry Pi will run a lot smoother and faster.
Note: Setting the arm_freq to 1100 will also work just fine but you have been warned about overclocking your device!