I came across this issue in my dell laptop (linux) where the laptop slowed down as soon as I was putting it to charging. This is generally counter-intuitive where you would expect the performance to increase on connecting it to power. I believe Windows OS even has settings where your laptop can move to high performance if plugged to a power source.
On searching the internet and going through my system logs, I was finally able to resolve the issue.
The solution turned out to be pretty simple:
Open the local.conf file, typically in the location-> /etc/modprobe.d/local.conf
Edit the file and add the following line:
You need to save the file and restart your computer.
It worked like magic for me :)
Have come to know from a friend that the problem is not restricted to Linux OS but also extends to windows. We are trying to investigate the issue and will post if we get a solution to it.