Bluetooth Slows My Wifi Connection

For the longest time, I couldn't figure out why my wifi speed is so slow compared to every other devices I have (Macbook, iPhone, Android tablet).

I inadvertently turned off my Surface Book bluetooth one day, and, BAM!, I regained full wifi speed.

So, now, I only turn on bluetooth when I have the need to use the pen.

Anyone else have this issue? Is this a hardware or software issue?