Also, the statement "Your rates have been changed for the best performance!" is not true for everybody that connect to your server. You are likely making it worse for some people.
Also, the server has a way to to set player's rate, no plugin necessary!!! Simply set the follow cvars for your server and it will force them to use the rates you specify:
Set the minimum and maximum for the range of values that you feel are acceptable. But remember, if you force people to use too high or too low of rates, you could actually make their performance worse.