sysinfo and hardware sensors

sysinfo gives one API over very different system interfaces: /proc files on Linux, system calls on macOS and Windows APIs on Windows. Create one System value, refresh the parts you need, and read CPU load per core, used and total memory, swap, disks, network interfaces, processes and, through Components, temperature sensors where the system exposes them. It also supports Android, iOS and FreeBSD.

Usage figures are measured between two refreshes, so the first CPU reading is not meaningful; keep one System value and refresh it on a timer. Beyond what sysinfo covers, readings such as fan speeds and GPU load depend on the system and its drivers, some need administrator rights, and GPU details often need vendor libraries such as NVIDIA's NVML.