CS sags very much (Counter-Strike)

After updating Windows to 8.1, installing the programs I needed, etc., I decided to go to the CS. I chose any first server I came across, I go in and see - everything is jerky, it's impossible to play, fps 8-10. I look in the task manager - under the hl2 process like this say "allocated" 150 MB of RAM, it does not go further. On 7 Windows, KSS took 500 - 700 MB of RAM (roughly speaking). Now I'm sitting in confusion. Tell me what to do. PS graphics settings are minimal, weapon models are standard