As it’s named, kidle_inject is a process to inject idleness to processors.
On a good day, this will keep idle your processors, lower processor temperature, and save your battery.
On a bad day, it will consume your processor somewhat like 50%+ on all cores, slow down your laptop, and drain your battery.
But, you can control this. Many new Intel-based processors could use intel_pstate driver to manage processor power consumption. If you use intel_pstate, you can drop intel_powerclamp (which would run kidle_inject). help your laptop to consume less power.
# modprobe -r intel_powerclamp
Or, consider to put
in your /etc/modules (or modprobe)