I am not sure but my server pretty much laggs alot.

I am on a 2.5GHZ cpu 2G ram
Hosting company : Cobrahost
Also i have a Pi with hyperion engine and did some stabilty services
20 people online only takes 150Mb of ram

Is it my server or the Vps? becouse i am pretty sure the vps should be able to hold up the amount of players easily..