Istio side car performance 1.2.3 impact : performance degrades over time

I had raised a github issues . Please check the following link. But I am not getting any update.
https://github.com/istio/istio/issues/15981 .

We are facing performace issue with the istio side car.
Without side car :

  1. client simulator (vegeta) to send GET/POST request -> application pod using pod service IP
    In statistics we can see it is able to reach 8k tps for 8-12 hours long run . it was stable for 8-12hours.
  2. Side car attached to the pod. (we have mTLS disabled)
    client simulator (vegeta) to send GET/POST request -> application pod using pod service IP.

In grafana we can see it was reaching max 3k . So 50% performance drop. BUT our main problem is that it is DEGRADING OVER TIME.
at the end of 8 hours end it was around 200. …

Same thing happens if we send 500 tps only … it is stable for 2 hours. then it drops … The screen shots are attached in the github link.

We have tried to disable the mixer , mentioned in the github link… But no improvement .
Kindly help me out.