High VAR and Fps Drops


Hi freinds. I have some problems in CS:GO. Sometimes my var(in graph, near the fps) increasing to 70 and it effects fps. My fps generally 40-50. and fps drops to 5 or 0. When its 0 game freeze for 2 second or more. So how can ı reduce var ms ?? Please help me and ı am so so sorry for my English.