Hi,
that’s a somewhat vague description of your issue like “my car is broken”. 
So, could you give more details
- What you’re doing when you find the performance issue?
- With what measures/experiences you compare the current situation, so you think of a deteriorated performance?
- As first troubleshooting have you ckecked [How To] Check Network Performance with iperf3, so you can isolate the issue to a general issue of the underlying network stack or it is more related to higher protocols like NFS, etc.?