Why the bluetooth Mac slows down under heavy load?

Hello!

Have long been experiencing the problem that on the Mac under a heavy load percent (50%), slow bluetooth. And so slow that the keyboard is impossible to use it (I have BT) keyboard. Accordingly, can not talk through facetime on the phone (via iPhone)
Also brakes Bluetooth are observed when a large network activity (downloading a large file from the server, for example)

The data on the laptop:
MacBook Pro (Retina, 15-inch, Late 2013)
Processor: 2.6 GHz Intel Core i7
Memory: 16 GB 1600 MHz DDR3

Data on the bluetooth adapter
Apple Bluetooth Software Version: 4.4.5f3 17904

Manufacturer: Broadcom
Transport: USB
Chipset: 20702B0
Firmware Version: v118 c9121

Actually, the question is, could this have something to do? For example, to reflash the chip, or buy a newer (if any)

Thanks in advance