So I have a pretty decent Pc, but any time Viper wall goes up or Raze grenade goes off I drop down to like 90-100 fps instead of my normal 200-220.. are there any tips anyone has to seize this? All of my settings are on low

I've been in a team for a pretty long time now, and just found out that they will drop me...Now i just feel disheartened and don't know how to react.

Im immo1 but i still struggle at this. I keep my pre aim at headshot level but at times i notice myself bring it down so when I shoot my first shot it is always hitting the body first. Any tips? Does it have to do with mouse control?