Game launch options can be used to change game settings before running the game.
Launch options allow the user to supercede inner settings of the game.

1. Right-click on Counter-Strike: Globel Offensive under the Library in Steam and select Properties.
   
   
2. Under the General tab click the Set launch options button.
   
   
3. Enter the launch options you wish to apply (be sure to separate each code with a space) and click OK.
   
   
4. Close the game’s Properties window and launch the game.

• -console
  It enables console as soon as you launch the game.
  
  
• -novid
  Removes the Valve introduction movie when the game starts.
  
  
• -high
  This will start the game in the high-priority mode for better FPS. It will make your PC set it’s priority higher over other apps.
  
  
• -threads
  Set its value to the highest number of cores of your processor for maximum FPS but I won’t recommend you to use all of your cores as it can be dangerous.
  
  
• -tickrate 128
  Allowing you to run your own dedicated server at 128 tick rate. This is good if you practice on offline servers. The tick rate will be 128 instead of 64.
  
  
• -fullscreen
  Loads the game in fullscreen mode.
  
  
• -windowed
  Loads the game in windowed mode. (-w [width] -h [height] -x [horizontal position] -y [vertical position])
  
  
• -noborder
  Removes the border around a window.
  
  
• +fps_max 0
  Sets your fps to max.
  
  
• +cl_interp 0
  Sets interpolation value
  
  
• +cl_interp_ratio 1
  Sets interpolation ratio
  
  
• +rate 786432
  Sets your client rate to 786432 and adjust accordingly if you are playing at 64/128 tick servers.
  
  
• +cl_updaterate 128
  Sets your update rate to 128 and adjust accordingly if you are playing at 64/128 tick servers.
  
  
• +cl_cmdrate 128
  Sets your command rate to 128 adjust accordingly if you are playing at 64/128 tick servers.
  
  
• +mat_queue_mode 2
  Forcing Your CPU To Use Multi-Threaded Mode.
  
  
• -freq 144
  This launch options forces your monitor to run at a specific refresh rate while playing the game. Set its value to your monitors highest refresh. For instance, if you own a 144hz monitor you can use -freq 144
  
  
• -refresh 144
  Sets the refresh rate of your monitor. Use the hz of your monitor.
  
  
• +cl_forcepreload 1
  Preloads The Whole Map & Sounds resulting in faster map load times.
  
  
• -nod3d9ex
  Reduce dxlevel 9 extension and helps to remove strain on GPU.
  
  
• -nojoy
  Removes the joystick support and give more free Memory and FPS.

The launch options underneath are the most effective launch options promising a significant FPS boost. I am using these myself and has experienced a generous increase in FPS.
WARNING - YOUR NEED TO ADJUST THE SETTINGS TO YOUR EQUIPMENT

• -novid -high -tickrate 128 -freq 144 -refresh 144 -processheap -noforcemaccel -noforcemparms -noforcemspd +cl_interp 0 +cl_interp_ratio 1 +rate 786432 -nojoy -nod3d9ex +cl_forcepreload 1 +mat_queue_mode 2 -nocrashdialog +cl_updaterate 128 +cl_cmdrate 128