No worries mate, there is a lot of people having the same issue (me included) and the reason is probably due the last cs update, everytime valve release an update of this kind (including a new map) they break the game and make players have bad performance, even if you have a good pc.
So all i can say, its just wait till they release and update and fix the game they broke...

true it is a bad fps since the bullets don't go where you aim. idk why they made most of the guns rng based