Latitude E6440 Performs Slowly When Plugged In

Hi, I have a Dell Latitude E6440 lap that my work has provided me.  It normally performs extremely slowly when I plug a charger into it.

The problem began, I think, when my original charger broke, and my work provided me a new one.  Our help desk insists that the charger is the same as the one I originally had.  I have tried purchasing my own chargers with varying voltages, and using the chargers from my co-workers' laptops but none of them seem to fix the issue.

What happens is this: when I plug a charger in, the battery icon in the bottom right of the screen almost always tells me the laptop isn't charging.  When this happens, if I look at the "Performance" tab in task manager, I can see my CPU speed drops to 1/4 of its normal speed.  When I unplug the charger, the speed slowly climbs back up to its normal speed.

I've had this problem (and laptop) for years.  I find that if I leave the charger unplugged mostly, and then randomly plug it in and certain times of the day, then the computer will eventually realize that it is charging, and have its normal performance.

So the computer is mostly functional, but it sure is annoying.  Is there anything I can do to fix this?

By the way, the problem is similar to these other posts I found, but none of them have a resolution:

https://www.dell.com/community/Laptops-General-Read-Only/Laptop-3x-slower-when-plugged-in-Unrecognized-adapter/td-p/4471820

https://www.dell.com/community/Inspiron/Inspiron-3558-lags-while-charging/td-p/6165523