inspecteur inspecteur shows what runs on a Linux machine and lets you act on it: processes grouped by app, live performance graphs, systemd services, startup programs, network connections and the system's details. One small native program, on screen in about 270 ms.

Screenshots

inspecteur's Processes section: apps with their icons and their processes, background processes, CPU and memory cells shaded by load
Processes: apps first, each with its processes under it, then the background; the busiest cells shaded.
The Performance section: one graph per logical processor
Performance, per processor
The Properties of a process
Properties of a process
The Services section: systemd's services, their state, and the selected one's journal
Services and a service's journal
Every process under its parent
Every process under its parent
Three processes selected, their kill asked first with each one listed
A kill of three, asked first