Fps Drop when i Join Server

Alright So from last few days, whenever i join any server, When i press any button to wokeup after joining the server, my Fps went from 40 to 1, and repeats the same sequence again n again. Please help !

my Laptop specs are:

8GB ram
GT555m 3GB
Win 8.1

does it crash at all?

No there is no crash at all, its just fps that goes from 40 to 1 than again repeats. so i force close the game via Task manager.