Netflix gives an answer to the question “You login to a Linux server with a performance issue: what do you check in the first minute?” in Linux Performance Analysis in 60,000 Milliseconds.
The short version:
uptime dmesg | tail vmstat 1 mpstat -P ALL 1 pidstat 1 iostat -xz 1 free -m sar -n DEV 1 sar -n TCP,ETCP 1 top
They provide a short discussion on each tool.
Anything else you would add?