Can I manually limit the %CPU used by a process?

Question

I would like to limit the amount of CPU time dedicated to certain processes (e.g. Firefox, Safari, ...).

I can't understand why such programs, even when not used (nothing loading, no animations, running in the background, ...), are so resource hungry. Why a browser must eat 50% or more of my CPU? Can I limit it to 10%?

Thank you.

Answer 1

You can monitor a series of processes by name by running the Bash script below. I'm not quite sure how to turn this into a login item since cputhrottle requires superuser permissions. Run it as a script, in an Automator workflow, whatever:

# Get the Process/App names from Activity Monitor and put them here
apps=("AppOne" "AppTwo" "AppThree")
# Set the respect limits here
limits={30 40 50)

while true; do
  for ${app} in ${apps}; do
    for ${limit} in ${limits} do
      for pid in `pidof ${app}`
        sudo /path/to/cputhrottle ${pid} ${limit}
      done
    done
  done
done

Answer 2

You can indeed! There's CPUThrottle, which allows to specify a PID to restrict.

Note, they're trying to use that much for a reason, it's a useful tool but whether it'll make it better or worse for you on a day to day will be something you discover.