This tool is a great idea. On recent computers your only choices are: powersave or performance.
That looks stupid compared to automatic CPU throttle that we had before.
So, similar to the author of this tool, I also waste time to switch my computer from powersave to performance depending on my tasks and if keeping battery is critical or no. Like when traveling without power plug.
Also, maybe I use it badly, but with cpufreq in have to manually change all the state of all cores individually and can do a single command to change all of them!