For unknown reason, I can't answer this (old?) thread:
https://forum.thegamecreators.com/thread/219938#postHolder
I also found the same issue here : https://forum.thegamecreators.com/thread/213601
I am also experiencing slowdown during the PlaySound command.
My actual Android phone is an Oppo Find X.
The slowdowns are also present on my Sony Xperia F5121.
Like the guy in the previous thread above, it's not about the code, but it's really the Playsound command with some devices.
There are no slowdown with the same code on my Samsung Galaxy S6 (which is quite older).
I sure of that. I took an old code from 2016, at that time I wasn't experiencing slowdowns, and I had the Samsung Galaxy S6.
With the latest AppGameKit Classic or AppGameKit Studio version, I don't have any slowdown with the Samsung GS6.
When I execute the code on the Oppo Find X (Android 10) or the Sony Xperia F5121 (Android 8) , I get slowdown during the playsound command.
Of course if I remove the Playsound command from the code, I don't have any slowdown anymore

(but that's not what I want)
I hope somebody will bring a solution. I don't like the idea of a game running slower on newer devices.
Thanks