Is it normal for bluetooth devices to stop responding when CPU is too busy? I have MacBook Pro 13" mid 2012 with 16GB RAM and 256GB SSD, Mojave 10.14.1. my Magic Trackpad 1 and AirPods get slow when CPU is too busy, especially when cpu percentage is above 70%. My USB-wired keyboard and mouse seamlessly work even if it is too busy. I wanted to try Apple Hardware Test for more details, but it says the error code DEC400 so I can't do that. I have an appointment at Genius Bar to check for my Airport card this Friday. I am worried they refused to fix it just because my mac is too slow.

EDIT: When executing Java programs from IntelliJ IDEA, sometimes Bluetooth devices get slow but sometimes work well. Maybe some other factors makes them slow. I had the same problem when I worked on Sierra.


I've checked out from event logs from Bluetooth Explorer. I think it tells me a lot. I am not sure exactly what they indicate, though. 

What I found out from Bluetooth Explorer


Mac drops the connection to the AirPods from some reasons. logs says the reason is 0x08. I think Google and Apple official user guide are both silent on what the reason code indicate. Some other factors somehow affect my AirPods, as well as a busy CPU.
When the CPU is too busy, the Throughput graph goes down dramatically.
Since I can not pinpoint your BT problem ...
I suggest you try this great tool provided by Apple.

You have to download Bluetooth Explorer as part of the 'Additional Tools for Xcode' package that's available (registration required) at https://developer.apple.com/download/more/. 

Go to that link, then search for 'Additional', and find the Additional Tools package for the latest version of Xcode (you don't actually need Xcode installed to use the Bluetooth Explorer app!).

Among other tools available, Open the Hardware Folder and select the BT Explorer.



Use it to determine your BT performance while you are running the IntelliJ IDEA.