Im blessed with 40-50 ms (milliseconds) ping to server almost all time.
When server is full it may show ~60-65 ms.
I am sorry you dont have the same. Anyway my example shows that the server is not your problem not is it the server`s backbone. Else i would also have higher ping, atleast a bit.
If you have 300 ms ping you face the fact that you have 10-30 Hop`s inbetween your box and the server.
Anyone of thouse Routers/Hops in the Internet structure can cause lag. Now Legend is that Network Packets are moved efficiently on best route but that is a lie.
Internet service provider is big money around buying bandwide on backbones that other companies own and selling that as little parts to you.
Now guess how your Internet service provider makes money...right, he promises you elite pro highspeed for cheap but all you get is just as much as you take without complains.