Do you know what kind of CPU and GPU your computer has?
Did you tried with the Chrome browser again?
If you use the program above, the audio settings can be configured by executing it with the --frames argument fas.exe --frames 1024 this will execute it with an audio buffer size of 1024, it is set to 256 by default but maybe it is too high.
The audio on Firefox still have issues and i have not found a good solution yet.
I will try to focus on performances again and on a GUI to change FAS parameters as well, i hope to enhance the accessibility which is a major issue right now as you can see.