That should be more than enough.
Then if it's slow, you should turn off som desktop graphics in the graphics card setup. Like Vertical Sync to Off. And also lower everything else, depending on your graphic card.
Anything to boost up the game.
Do you know your fps in the game? It should be 100fps and sometimes switch between 100 and 98fps.
Use the "cl_showfps 1" command in the console to easy see your fps. Also the "fps_max 100" will set the border.
Also in game options, turn off A3D sound if you have it active. This sound engine is way to laggy.
And in advance player setup, lower the decal level to 150 instead of 300 thats default.
That's how you mainly boosts the game.
Have to go!
But see to when you host the server, mark the "Lower Ping Server Physics" or what it called.