Surface Pro 4 running slow on charge

[Born_2_Kill_83]

All is well with my Pro 4 until I plug it in to charge, even worse when the battery is low and I'm charging, the laptop OS runs a little slow but the main problem is a massively slow wifi connection. I go from my normal ISP 112mbps to about 6mbps which means I can't stream from the laptop and the internet is very slow. If I unplug I see these numbers slowly climb on speedtest.net again but when the battery is low it's still quite bad off charge. Is it due to go on the bin soon?

 

[MM-Seat]

I'd probably be inclined to put a fresh install of windows on it.