Shuffle issue

not sure if it's an issue, or just something i'm doing the wrong way but..

with a huge amount of songs (>> 1000 items), the shuffle function of my  player (Version 0.07 (r635)) looses efficience. That is.. it seems to fallow the locality principle, that is physically admissible but statistically improbable in a random procedure! It almost never skips out of a range of 50/60 songs from the actual one, rather choosing a near song to the playing one than a far one. The result is that starting with song #1 the items from 600 on are almost never accessed.

Is there an explanation?