that's a pretty awesome summary. to that i would add:

* `iftop` that allows me to quickly check which network streams are hogging the machine (this is a little like sar -n DEV 1 but much more detailed!)

* `tcpdump -c 100 -vv`- poor man's alternative to iftop or systat if they're not available locally

* tail those logfiles, with systemd it's even easier with journald as all logfiles can be checked at once: `journalctl -xf -p notice | ccze -m ansi` (ccze colors the output, purely optional)

* probably more i am forgetting now

the great takeaways in the article for me are:

* pidstat: great to have an average, beats top for sure

* back to basics: hit dmesg, vmstat and iostat first, as you learned in the beginning! :)