What exactly is the Audio Switcher in MPC-HC and what does it do?

[Deathbliss]

OK to start with I have followed this guide:
http://www.avsforum.com/t/1357375/advanced-mpc-hc-setup-guide

I played a file and the audio stuttered, the frame rate as well was affected. I have a Windows 7 64-bit OS, running 32-bit versions of everything as instructed, and I have these system specs:
MSI Z77A-GD65 Gaming Motherboard
Intel Core i5-3570K Processor
XFX Double D FX-787A-CDFC Radeon HD 7870 Video Card

Previously the file played fine in VLC. I Googled around and found someone said something about the Audio Switcher. I had unchecked it, so I rechecked it based on this fixing the issue for that user. It also fixed the issue for me. I was playing a .mkv file however.

I just want to know exactly what the Audio Switcher in MPC-HC (Media Player Classic - Home Cinema) is, what it does, and what effect, if any, it will have on the LAV Audio Splitter. I am also confused about the enable/disable bit mentioned in the guide. Do I check it to enable it or disable it? Well its a moot point, if I uncheck it no HD file will play on my computer. Still would like to understand this however.

Thank you for your time!

[paradoxical]

The "Audio switcher" does exactly what its name says. It lets you switch between audio tracks in a file.

[mindbomb]

it doesn't really do anything affecting performance directly, but it could be preventing a problem causing audio renderer or a problem causing audio decoder from being used. Different audio decoder could be because of different splitter being used instead of lav splitter.

make sure lav audio decoder is set to prefer in external filters.
also, make sure lav splitter is being used when you right click inside the window and go to filters.
make sure audio renderer is default directsound device or reclock.