Server Lag and Tickrates

[Gateway Network]

Why does my server lag so much?
My Server SPEC's
CPU:  Intel  Xeon E3-1270v6 - 4c/8t - 3.8GHz /4.2GHz
RAM:  32GB DDR4 ECC 2400 MHz
↓ Server Collection ↓
http://steamcommunity.com/sharedfiles/filedetails/?id=1196532275

Each time you'd fly a WAC aircraft the server would lag you causing you to crash the aircraft not to mention it lag everyone on the server, sometimes the server would crash. This isn't the only thing crashing our server or causing lag, The Cars lag to the point where they're useless. they also lag everyone, They even crash the server when it theres are more than 1.

I would really like to resolve this, So Please Help Meh!