Laptop s CPU drops when charging?

So I've been having this problems since September 11th about my laptop being awfully slow when it is charging. I've been searching up everything but nothing will work. All my plugged in settings are "High Performance", but it is still slow when I'm charging. I've bought 3 chargers so far (wasted my money), but it doesn't work. When it's unplugged it runs very smoothly and fast.

Laptop: Intel(R) Core(TM) i5-5200U CPU @ 2.20GHz ( Lenovo Flex 3)

Think of this… You are charging the battery while using the laptop… Soo-o-o-o-o some power has to go to the battery and some has to go to the computer… And high performance only eats into power even more…

Maybe this helps