Maybe not helpful as I don't have much debug info. I'm running Arduino 1.8.9 / Teensydino 1.47 under Linux Mint on an Intel-based "fitlet2" mini-PC.
Linux john-fitlet2 4.15.0-58-generic #64-Ubuntu SMP Tue Aug 6 11:12:41 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
I didn't even have a Teensy connected today, I was just trying to program an Arduino Uno which didn't work for some reason, then a Mega which eventually did. Then I closed down all Arduino windows. Only later did I notice a process named "teensy_post_com" was still running, and it was consistently taking 100% CPU according to 'top'. Never seen that before, just thought I would mention it in case of interest.
Linux john-fitlet2 4.15.0-58-generic #64-Ubuntu SMP Tue Aug 6 11:12:41 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
I didn't even have a Teensy connected today, I was just trying to program an Arduino Uno which didn't work for some reason, then a Mega which eventually did. Then I closed down all Arduino windows. Only later did I notice a process named "teensy_post_com" was still running, and it was consistently taking 100% CPU according to 'top'. Never seen that before, just thought I would mention it in case of interest.