Lag in combat on hit

Since betrayal I've noticed that when i enter combat my latency and fps start to fluctuate rapidly. Specifically it only happens when i hit things. If im using a damage over time skill its barely noticeable but when I use something like tornado shot, it starts playing up and then when i stop attacking again it goes back to a stable latency and fps.

Is there any fix for this? I've updated my drivers and tried lower the settings as low as they go but it hasn't fixed the issue.

Is incredibly frustrating because now im limited to DoT builds