1. First check the ping to your server.
2. Is your server in your local network? If not, check the speed of your internet connection.
3. Maybe server is running some script all the time, and is very busy because of that.
Maybe you added any jobs in "crontab"?
4. type "top" to your console, and check which process takes lots of memory
5. Try to reboot the server.
Hope it helps..,