Resource Monitoring Tools

There are programs available to watch various aspects of your system.

iftop

See active internet connections. e.g.

iftop -i eth1

Will show you websites that don't close a connection, when the tab is left open. A privacy and security nightmare. This is a reason why Javascript is bad.

vmstat

See RAM usage. Can be watched, to monitor swapping. e.g.

vmstat 3

Leave it running. It will update every 3 seconds.