I'm running Kubuntu 18.04, and I want to do some system profiling. My main goals are to improve startup speed and power usage. What instruments can I use to profile daemons/processes to get the time they took on system startup or see their usage of CPU during normal operation? It would also be great if I had some tools to monitor disk/network usage, since these operations are pretty battery-hungry too.
For your boot performance, see
systemd-analyze
.Your network chip likely uses a lot less power than your display.
From my recent experience with Kubuntu 19.10, a good deal of power is wasted by the external GPU. If you have a system with both an integrated Intel GPU and an external NVidia GPU, there are ways to activate the NVidia chip only when needed (google for "optimus").