PlayOneShot - skips and doubles the sound.

I've run into an awkward problem. I'm using PlayOneShot for some sounds in my code. The problem is - after playing a few sounds in a sequence, where a sound starts while the previous one is still playing (overlaping each other), the sound starts to "clogg up". The AudioSource skips some cycles and then plays them with a lag of a few seconds.

Now, before I start checking my 90-pages-long code - could this be caused by some Unity bug of PlayOneShot, or could this only be caused by a bad code?

Is there something I'm missing in the theory behind PlayOneShot? All sounds are in WAV, around 100-300 kb each.