[PSS]

You CPU load is not high, it's only 4%. Load average (5min) is a bit high, but not abnormal.

try shell commands:

top

it shows realtime values. quit with q. Press s +2 to set 2 second sampling interval.

ps auwx

It'll show all processes and what is running them.

free -t -m

shows you memory usage in MB:s. Normally nearly all memory should be used in Linux, but swap only by a little amount (2-5% of swap size). If you're swapping a lot it will kill performance.

It's hard to say anything specific as we don't know what scripts, databases, traffic do you run, and how.