Egad! You're running with an Intel Celeron N2830 -- it's a dual-core 2.16 GHz CPU -- it's definitely not up to the task of running that in high performance mode.

Anyway, how are you running the 'low performance' mode? Are you running Outpost.bat? Because it works okay on my end.
If it still isn't working when you do that, you can edit the 'high performance' configuration file:
Open
'Outpost-high.conf' with any text editor (notepad will work fine).
Scroll down to the section labeled
[CPU].
Change the line
'cycles=fixed 60000' to
'cycles=fixed 25000'.
Save the file, close out the text editor and then try launching the 'high performance' mode again. Hopefully this will resolve some of the sound issues for you.
As a side note, because of the reduces performance, you may still end up with scratching or popping. This was present back in the early 90's as well on low end machines -- there's not a whole lot that can be done about it atm. I'm going to work on an updated package at some point to improve compatibility and take some suggestions that others have mentioned in maybe making it work better / more streamlined.
Couple of side notes:
Ctrl+F10 releases the mouse. Alt+Tab also works.
Alt+Enter switches between fullscreen and windowed mode.