lot of lag

so i opended my map today and it lags like hell i dont have much props or brushes and before this it was smooth and good how to fix?

edit fixed lock and move thread

Are you running any games while trying to work in hammer?
Do you have hammer running at dxlevel 81?

Next time post in this thread instead of making a new thread

is radius culling enabled that can sometimes lag hammer https://developer.valvesoftware.com/wiki/File:Radius_culling.png