This has been an object of my curiosity since I began playing LFS in its infancy. What purpose does the "sound lag" feature serve? Ideally, I would like to set it to zero, but the setting allows only as low as 0.05 not a big deal, I just wish to humor my OCD personality!

Thanks in advance

LFS generates sounds by writing into a memory buffer which is read by your sound card. Sound card loops over the buffer and plays its contents. LFS has to write into the buffer slightly ahead of the position the sound card is reading. Sound Lag sets how much ahead of that position LFS writes.

This is at least how it used to be before the big Vista compatibility patch. LFS has been using DirectSound instead of waveOut since then, but the basic principle probably hasn't changed.